She is voiced by Kaori Nazuka in the Japanese version of the anime, and by Stephanie Sheh in English version of the anime.
Eureka is a girl born by the Scub Coral, a race of assimilating, intelligent lifeforms that landed on Earth via a falling satellite (which was also named EUREKA) and is, therefore, a humanoid Coralian. She is the pilot of the LFO called the Nirvash TypeZERO. Eureka treats the TypeZERO not as a machine but as a companion with thoughts and feelings of its; own. Initially, Eureka knew nothing of her origins or her true purpose before joining the Gekkostate due to her being born with no memories. She was found by Adroc Thurston, a famous military scientist, who named her Eureka and taught her how to be an LFO pilot after realizing she was the perfect pilot for the TypeZERO, whose archetype was found alongside her, and he took on a father figure to her until his disappearance.
A bit of an enigma, Eureka is a girl who has trouble communicating with and understanding humans. She tends to speak calmly and bluntly, and due to her initial lack of empathy, she came across as being blunt. She is often perplexed by other people's emotions and behaviors, making her naïve, especially when it comes to interpersonal relationships. She is considered to be one of the most excellent LFO pilots due to her being the TypeZERO's pilot and once being part of the United Federation's Special Operations Forces until she left with Holland. Eureka ends up taking in three children orphaned during her time in the SOF, becoming their surrogate mother and learning a bit of humanity. However, her physical and mental states undergo several changes after meeting her partner and future husband, Renton Thurston, due to the strong feelings of love he harbors for her. Even though Eureka is blunt and emotionless, Renton takes an immediate interest in her and his gentle, amusing and determined personality becomes the thing that changes Eureka's character.
Initially, Eureka didn't return Renton's feelings because she did not understand what they meant. However, as she gets to know him and sees how far he is willing to go for her, she begins to fall in love with him and she realizes she wants to be together with him forever. Eureka marries Renton at the end of Eureka Seven and become the official adoptive mother of Maurice, Maeter and Linck.
In Eureka Seven: AO, Eureka has two children with Renton: a daughter named Amber (died three months after the birth), and a son named Ao.
At the beginning of the series, Eureka acts extremely distant and odd with others due to that she had very little contact with humans outside the military. Because of her lack of emotions, she was very blunt and serious, nonchalantly going along with anything Holland told her to do without questioning his judgment. However, things changed when she met Renton; Eureka saw something different in him as a person when she discovered that he was also able to pilot Nirvash with her. As time went by, she started acting less of a socially awkward girl and more like an actual teenage girl as parts of her human side started to emerge. However, she became passive and weary due to her believing Renton can pilot the Nirvash better than her, causing her to feel unwanted and hopeless. This also caused her to reject and ignore Renton, never realizing she was simply jealous of him and lonely that her partnership with Nirvash was strained. After Renton saved her from getting absorbed by the Scub Coral, she slowly changed from uncaring to sympathetic as she started to understand the hardships Renton endured for her sake. After learning Renton defected, she burtsed into tears and fell into a deep depression as she blamed herself for him leaving and she realized how important he was to her. When they were able to meet again, Eureka declared to Renton that she had "chosen" him as her lifetime partner. Despite being happy with Renton, Eureka feels guilty for dragging him into a war and staining his hands with blood, and she develops a strong desire to make him happy with her.
Through her relationship with Renton, Eureka undergoes a major change in her personality in order to atone for her sins and become a better person. Although initially afraid of the change in her, she decided it was best for her and she comes to believe in Renton with her entire being. In season 3, when she is able to connect feelings of guilt with her worst memories, she becomes less confident and depressed, although she says that all she needs to move forward is having Renton by her side. It is his emotional support that allows her to try her best, no matter how bad the odds were against them.
In AO, she becomes more human-like and is always seen smiling. She is more kind, helpful, and no longer naïve, but she is still shy about her friendship with Renton; she blushed and got embarrassed when Elena mentioned the moon with the heart on it from Eureka's world and when Ao asks who the father was of her unborn daughter. After becoming a mother, Eureka is very loving and caring towards her children, so much that she is willing to risk her life to keep them safe. She is constantly concerned for Ao's well-being and hides her sadness that stems from Amber's death so that Ao would never learn the circumstances to her death. Eureka is also very protective of Ao; in the manga, despite being in holographic form, she challenged Truth and was enraged at him for trying to kill her son. Because her son and daughter are the most important people, next to Renton, in her life, she was willing to sacrifice everything else that was important to her, including her relationship with Renton, to protect them. However, she always believed that Renton would come back for her and Ao, and he was risking so much to protect them while she stayed behind to raise their son and attempted to risk her own life for his, proving herself as a loving wife and mother.
Fourteen years before the series began, Eureka was found in a mine along with the archetype of the Nirvash TypeZERO and she was brought to Tresor Laboratories for study. It was found that while the Nirvash wouldn't well with any human at the controls, it responded well to Eureka as the pilot. Soon afterwards, she met Adroc, who taught her how to walk, talk, and interact with others. His influence on Eureka was that of a father figure. After Adroc's disappearance in the First summer of Love, the then Lieutenant-Colonel Dewey Novak had Eureka placed in the care of his younger brother, Holland, who trained her to be an obedient child soldier. They were both assigned to the SOF so that the military can use Eureka's piloting skills for their benefit. During this time, Eureka grew to trust Holland to a degree equivalent to her trust of Nirvash, but she was still emotionally detached and unaware of her sense of self. Three years before meeting Renton, Eureka and the SOF were given a mission to eliminate all the people living at Ciudades del Cielo under the assumption they were terrorists for protecting the Coralians, and Eureka agreed to participate because she believed in Holland. She killed many people until she found three children, still alive but traumatized, in the pile of corpses. Awakening t her senses for the first time and realizing she had killed people, she decides to protect the children. Taking them to Nirvash, she rendezvous with Holland who was talking to Master Norb of the Vodarac. Later she joins him in a revolt against the United Federation , aiding in stealing the Gekko and becoming outlaws. She became an adoptive mother to the children and a respected member of the Gekkostate, but she never showed any emotion nor did she associate herself with anyone other than Holland and the children.
After being on the run for three years, Eureka is ordered to travel to Bellforest by Holland to collect the Amita Drive from Axel Thurston in disguise of having the Nirvash repaired. She crashed into the Thurston Garage and met Renton for the first time; Renton falls in love with her at first sight. The next morning, as she talks to Renton, she reveals she doesn't need a Compac Drive to operate the Nirvash as others do. Renton offers to lend his to her and inserts it in its place, revealing he is a mechanic who can understand machines also have feelings. Eureka surprises him by telling him that is common knowledge and goes to get a flame thrower so she can burn the remains of his room, which she destroyed in the crash, and give them a funeral, much to his dismay. She smiles upon seeing him having his shoes burned while trying to put the flames out. On the Nirvash, the Compac Drive doesn't work and she tells Renton to take it out since she never needed one and she explains she cannot believe in what she doesn't understand because nothing will come out of believing in something that doesn't mean something and that will lead to great misfortune. Renton tries to argue against her before Axel interrupts them by voicing his realization of Eureka being one of Holland's friends and produces a strange device that he knows is what Eureka wants. He goes on to tell her that his family was torn apart because of it, so she can take it but never return. Suddenly, she sensed missiles flying towards them and piloted Nirvash out of its restraints and away from the garage before its destroyed. She then engages the oncoming KLFs in combat.
Holland and Matthieu tried to join her, but they were kept apart, and Eureka tried to escape from the KLFs to no avail until the battle was interrupted by Renton's arrival on his ref board to deliver the Amita Drive. She saves him from being killed and finds him clinging to her as he confesses his love to her. She is confused of his confession and doesn't understand what love means. He pulls out the Amita Drive, explains it to her, and inserts it, which results in the Nirvash deactivating and Eureka falls unconscious for a few moments. Renton is unable to pilot the Nirvash because it wont respond to him and she wakes up just enough to put her arms around him and ask him to believe in her. The Amita Drive activates and the Seven Swell is released, defeating the KLFs and Renton falls unconscious with Eureka. Holland comes to retrieve Eureka and the Nirvash, and then he comments the power of the Amita Drive, and Eureka says Renton was the source of that power and they take him back to the garage. Seeing Renton smile in his sleep, Eureka asked Axel why he was smiling and voiced her opinion that Renton was being reckless. Axel tells her Renton may have been reckless but he will still compliment Renton because he is family, which confuses Eureka, and Axel tells her that she will understand when she becomes a mother. Holland interrupts them and gets into an argument while Eureka waits with Renton, who wakes up. After a conversation, Holland invites Renton to join him and Eureka on the Gekko. Eureka adamantly asks Renton to come with them because she may need him and he agrees. Holland sees Eureka holding hands with Renton and she says they need to get back to the ship. Holland objects and tells them he will read the waves in case they need to make a forced escape, but she says she will do it. Surprised, Holland asks why because she wasn't feeling well earlier, but she says she feels better. Eureka takes Renton and shows him how to feel the waves, and she tells him that he reminds her of someone she knew well. After saying his goodbye to his grandfather, Renton left with Eureka and Holland. She comments to Renton that she has never felt the Nirvash as happy as it is now and, once aboard the Gekko, she introduces him to her adoptive children.
Initially, Eureka's time with Renton was difficult because she didn't understand his feelings of love for her. However, his presence on the Gekko caused a tremendous development on her physical and mental state, to the point where she gradually began to understand human nature and emotions. While she referred to Renton as a child and found him amusing, she tells him that she finds him interesting and truly enjoyed his companionship. When he is assigned to co-pilot the Nirvash with her, they form a special link together, in which they later learn is necessary to activate the Amita Drive, awakening the Nirvash and accessing the Seven Swell. In order to access the Amita Drive, Renton and Eureka must have an emotional agreement and equal wish for something. If their feelings are disconnected, the Amita Drive won't activate, even though Renton at times was able to activate the Amita Drive with Eureka resent but unconscious. During a brief stop to Ciudades del Cielo, Eureka became worried for Renton after he ran away when Holland assaulted him and she went searching for him. She was attacked by members of the Vodarac who called her a "monster" and "murderer". She then confessed to Renton her role in the massacre and the Gekkostate's mission is to atone for their sins and stop the military. she also tells him she needs him to help her pilot the Nirvash because she, remorseful of her past actions, wants to make amends and Renton is only person who can fly the Nirvash with her. Pressured by Renton to confront her problems rather than run away from them, they use the Nirvash to stop the military from bombing the city and he tells her she truly made an atonement, and he things she is the same person as she was before. Eureka cries for the first time in her life and she said she started to change from the moment he came into her life. As she continued spending time with Renton, she started developing human emotions and started smiling and laughing more, and unknowingly developed a need to have him by her side. However, this change in her started to scare her to the point where she questioned if it was alright to change because she knew no other way of living or interacting with others. She also wondered if the change was more or less benefiting or hurting her partnership with Nirvash as it began to respond more to Renton than her.
The Gekkostate comes into contact with Anemone and the Nirvash TheEND as they were investigating the appearance of a Kute Coralian. Aware of the danger and concerned for Eureka's strange behavior, Renton tried to get her to stay on the Gekko and asked her what a Coralian was. Eureka said she didn't know and said she would go, after Holland asked her what she wanted to do, because Holland told her to. While battling Anemone, Eureka and Renton, along with Anemone, fell unconscious after entering in the Kute Coralian and entered in a dream, with Eureka trying to find Renton, who was being ambushed by Anemone. Eureka saves him from being killed but suffers a physical and mental pain with Anemone. While tending to her, Renton's wish to protect her activates the Amita Drive and allow them to travel back to the Gekko. Several days later, Renton met with Eureka and Anemone within a house in a dream/hallucination. In the form of Nirvash, he defends Eureka from Anemone. After arriving at the Scub Coral mines to repair the Gekko, Eureka's mental state declines and fell into a massive depression, which caused her to distant herself from others and reject their efforts to help her. Around this time, Eureka began to question her status as Nirvash's pilot and believed it had come to favor Renton more than her and was troubled it no longer talked to her. This caused her to get jealous of Renton and ignore him. She later admits her helplessness and offered Renton to be Nirvash's pilot but Renton, feeling hated by his crew mates, rejects her. This causes Eureka to conclude everyone hates her and she wished for things to go back to how they were before she met Renton; she removes the Compac Drive and is sent deep into the mine. She allows the Scub Coral to nearly absorb her while concluding she has no purpose of living but then realizes how afraid she is and pleads for Renton to save her, which he does but she is left encased in scub. Renton subconsciously activates a Seven Swell to save themselves and get back to the Gekko.
A Vodarac priest is brought on the Gekko to heal Eureka, even though she loses most of her hair and receives scars on the left side of her body. While she recovers, Renton tries to make up with her and profess his love to her, but this scares her and she rejects him. This incident, along with the fact that none of the crew are concerned about his troubles, Renton decides to leave the Gekko. Once they discover him gone, everyone conspires to make sure Eureka doesn't find out, especially since she seems to have developed an interest in him (evident when she immediately started asking questions about love and why Renton hadn't visited with her). She has a heart-to-heart talk with Gidget and admits she is confused about her feelings for Renton, and Gidget concludes Eureka is falling in love with Renton. Eureka becomes more interested in this and continued asking everyone where Renton was, but they kept lying to her about him being gone. Ultimately, Holland was pressured to break the news to Eureka, and she was shocked and devastated, leading her to mourn his absence. During this time, she blamed herself for him leaving because of how mean she was to him and desired to see him again, and takes over his chores he was assigned to do because "he isn't here" and wears his tracksuit. The pain of being separated from Renton nearly overwhelms her to the point where she tries to pilot the Nirvash and go look for him, and broke down crying when it didn't respond to her pleas. Confronted with the fact that Nirvash needs both Eureka and Renton and that Eureka is depressed without Renton, Holland promised to bring him back for her sake. When he returned empty-handed and decided changing routes to avoid being found by Charles and Ray Beams was a priority, Eureka was enraged at Holland, leading them to have a heated fight. She correctly accused him of hating Renton and deliberately leaving him behind, also revealing she knew how he had treated Renton. When he said she was more important, Eureka rejected this and, no longer trusting Holland, left the Gekko to find Renton on her own. Unaware he was returning to the Gekko to warn the crew of the Beams' attack on them. She found herself in a dangerous situation against Charles and Ray, who tried to kill her. Renton launched the Nirvash and rescued her, and she confessed her feelings to Renton by telling him that he was truly her partner and she wanted to talk to him for so long, and he says the same thing. Since their previous way of fighting led to the deaths of people, Eureka and Renton decided to take a merciful method of combat by disabling their opponents. Nirvash responded to their feelings by creating a new waves that disabled every KLF in their path. They then start to talk about how the time they spent apart from each other made them realize that being together is most important.
As a result of leaving the ship and going into combat without permission, Eureka and Renton were sent to the brig with the kids. They were given bulletproof vests, gas masks, and a gun from Moondoggie as they prepared for the Beams to attack them. When the Beams invade the Gekko and send the ship into lockdown, Eureka and Renton put the equipment on the kids and wait for Talho to come release them and take them to a safer location. However, Ray holds Talho at gunpoint and became enraged to hear the kids call Eureka "mama" and tried to kill her; her hatred for Eureka stems from that Ray became sterile from the effects of the Seven Swell, and because Eureka was piloting the Nirvash when it released the Seven Swell, Ray blames Eureka for her inability to have a child. Renton tried to reason with her to stop while vowing to not let her harm Eureka and the kids, all the while Charles did from multiple gunshot wounds from Holland, and Ray escaped. While waiting for her to return to attack, Eureka tried to comfort Renton as he blamed himself for Charles' death and she asked him to go see Nirvash with her. Unsure what to say, she asked him what should she do and he asked her to rest, and she replied she has been sleeping since she stopped hearing Nirvash's voice. When Renton said the same thing, Eureka blushed and was amazed how alike they were. Ray tried to destroy the Gekko in a murder-suicide kamikaze attack before she is killed by Holland. Confused over the events, Renton blamed himself for the Beams' deaths and expressed his anger at everyone for how they treated him. Now understanding the hardships Renton dealt with for her sake, Eureka comforted him by telling she believed in him the most and she wanted to learn everything about him. Renton further demanded to know why Holland killed the Beams with the excuse of protecting him, and Eureka said it was because she picked Renton as her partner and Holland wanted to protect them. They then decide to stay together after realizing they can't bear being separated again. Although Eureka was happy with Renton, she was aware that Renton didn't want to rejoin the Gekkostate and his return was simply to reconcile with her. She wanted him to stay so they can be together and she was worried about him leaving again. To repay the crew members, they cleaned the entire ship and cooked for everyone. but Talho ruined the moment by explaining the true nature of Eureka - she is a Coralian. Eureka admits that she didn't tell him sooner because she was afraid he would reject her but he said he didn't care about it because she has been special to him since they met, much to Eureka's joy and relief.
Renton's continuing acceptance of everything about Eureka leads to a much stronger bond of trust, and Eureka comes to realize how much Renton means to her, to the point where she acknowledges that she is falling in love with him and wants nothing more than to make him happy with her. During their visit to Tresor to have the Nirvash repaired, Eureka and Renton watched a film about the origins of the Nirvash and how Eureka came to be Nirvash's pilot. Eureka tells Renton that she likes being with him because he makes her forget the terrible things she did but she broke down in tears because she feels guilty for dragging him into the war and staining his hands with blood. They attempted to share their first kiss but were interrupted when Nirvash rejected the repairs. Eureka insisted that Nirvash didn't want to be repaired to its original form and she relates how she has changed into a better person.Based on the research from Dr. Bear, Eureka learns the reason why she has no memories of her past prior to being found; the Scub Coral deliberately created her with a clean slate so that she can experience human behavior and emotions and forge her own human-like personality to help the Scub Coral understand the humans. Prompted by Renton's reaction to the Beams' deaths, Eureka begins to understand feelings of guilt and regret, especially towards the massacre at Ciudades del Cielo. She knows her past actions led to the deaths of many people, and because she beginning to understand the human impact of killing and loss, she loses confidence in herself and no longer wished to fight with Nirvash. Renton helps her realize they can only disarm enemy units and he constantly consoles her as she tries to deal with her past sins and take responsibility for them. When Dewey starts releasing the Antibody Coralians to destroy cities and kill people to gain public support, Eureka was saddened and blamed herself because it was her own kind that was killing people. Renton cheered her up by taking her for a ride on Holland and Talho's longboard and they happily rode it in the middle of the sunset. Holland announced his intent to disband the Gekkostate after completing their final mission of rescuing Norb from the military, but the crew refused to let him. Before going to the Capital, Holland spoke to Eureka and Renton because he decided to tell Renton how he met Eureka and Norb. In a carefully planned mission, they invaded the Capital but halfway through, Eureka became afraid of killing innocent people and forced the Nirvash into hiding. She then broke down to Renton and said she was afraid of what would happen to everyone and she wanted to run away from it all. Renton reacted by hugging her and telling her he will fight in her place because he wants to end the war for his own purposes, and this calms Eureka down and they proceed to rescue Norb while Holland confronted Dewey. After seeing Eureka and Renton piloting the Nirvash together and appearing to be happily in love, Norb instructed Holland to get them to the Vodarac Shrine so they can pass over the Great Wall and find a way to end the conflict between the humans and Scub Coral. Eureka becomes ashamed of her scars and, after learning how guys like girls wearing makeup from Gidget, she attempts to use makeup on herself to look pretty for him but felt humiliated due to using too much of it, and Renton said he loved her no matter what she looked like. Overtime, Eureka learns more about human nature, specifically pregnancy and childbirth, which intrigues her. She later finds out that she can also conceive, carry a baby, and give birth like a normal human, which strengthens her desire to have a family with Renton.
Days before arriving at the Vodarac Shrine, Eureka and Renton talked about what might be behind the Great wall and she replied "future" because its what Renton's father, Adroc, once told her. Renton was shocked to learn she knew his father before he died and he angrily shouted at Eureka for not telling him sooner, but she was confused due to not understanding family issues and ran away. This caused a misunderstanding among the Gekko crew that Renton wanted to have sex with Eureka and she was resistant, due to Eureka crying and wondering if she deserved to be with Renton and due to Renton looking at adult magazines for relationship advice. Hilda and Gidget took Eureka aside to talk to her (it is implied they explained the facts of sex and pregnancy due to her immediately asking Talho about her pregnancy and how Holland was going to be a father), and she finally starts to understand the meaning of a family. After reconciling with Renton, she revealed that Adroc released the Amita Drive during the First Summer of Love in order to stop it and his last thoughts were of his family before he disappeared. This revelation allowed Renton, who had thought his father abandoned the family, to forgive his father and Eureka thinks that Adroc treated in a fatherly way. Afterwards, Norb had the crew play soccer and, even though she never played before, Eureka excelled in it. She constantly cheered for Renton, except for scolding him once for making a mistake but she later apologized to him and offered to cover for his mistakes, much to his dismay. In the climax, she and Renton stepped on Holland's face tojointly score a goal. As punishment, they cleaned the hanger and Eureka told Renton that she said "I believe in you" to him during the game but he didn't hear her. She explained that miracles seem to happen when he is around.
The Gekko arrive at the Vodarac Shrine and Eureka refused to meet with Tiptory out of fear the Vodarac would never forgive her for her crimes against them, but pressured by Talho, she agreed to meet with Tiptory and to go through with the mission to get past the Great Wall. Initially they planned to enter the shrine in disguise but an incident with the kids accidentally activating Nirvash caused them to hastily get Eureka, Renton, Norb, and the kids through the shrine. Led by Norb, they met with the first humanoid Coralian, Sakuya, who explained her history to Eureka, including how she fell in love with Norb and failed to pass over the Great Wall. She helps restore Eureka's original appearance but Eureka requested that her scars remain to remind her of her hardships. Eureka later related to Renton and Norb that Sakuya told her that she and Renton need to be happy. They are then attacked by Anemone who tried to stop them from passing over the wall and entering into the Promised Land, but they managed to escape. Arriving at their destination, they are shocked to realize they have arrived at Earth and are unable to understand their purpose on Earth was, which caused a rift between them all. They wondered around the coastline for some time and come closer to the Scub Command Center. As a result, Eureka's scars began to turn green and Coralian features began appearing on her body. Thinking Renton will reject her, Eureka hid them from him. When he does find out, she ran away but he caught up with her as she broke down in tears and said she didn't understand why this was happening to her now that they are together and where they should be. Renton tried to comfort her but she rejected him and said she was not human and he didn't understand that. Angry, Renton went as far as to damage his own arm to prove his acceptance of her changing form, an act she found idiotic but hugged him. This emotional moment caused Maurice to lash out at them; at Renton for "stealing" Eureka from him and ruining everything, and at Eureka for running away from her responsibility in taking care of them after killing their parents. Eureka calmed him down by asking him if he hated her smile and assured him that she still loved him, Maeter, and Linck. Renton's wound got infected and he developed a high fever, and Eureka and the kids had to take care of him. Eureka was sad because she felt she wasn't doing enough to help him and almost tells Maeter and Linck the truth about their real parents but the kids insisted that Eureka was their mother no matter what. She suddenly grew butterfly-like wings and her left arm became green and pink of Coralian design. After Renton recovered, Eureka was surprised but happy to hear him say he thought she looked beautiful with the wings, which prompted her to embrace Renton and tell him that she loved him for the first time. From that moment, Renton and Eureka began contemplating their future, which included getting married, raising the kids together, and having children of their own.
Soon afterwards, Renton spotted his older sister, Diane, and ran after her with Eureka and the kids following him and they entered in a golden library greated by the Command Center. Eureka and the kids met with Adroc, who looked after them before Renton returned. They embraced and Eureka assured him that she will never leave him. When they exited the Command Center, Anemone appeared and attacked them to destroy the Command Center. In the fight, Eureka discovered Anemone's feelings of sadness and pain, and she convinced Renton to listen to Anemone and calm her down. After Anemone was saved by Dominic's arrival, all seemed at peace until Dewey fired his satellite cannon at the Command Center and destroyed it. The Gekko then arrived to rescue them but engaged in combat with Dewey's ship. After discussing their options, Eureka and Renton decided to take the kids and the Nirvash to become the new Command Center in order to stop the Limit of Questions. Holland engaged in a gun battle against his brother in order to end Dewey's madness but it ended with Dewey committing suicide. The surprising move activated the collars Eureka and Anemone always wore, which were designed to activate a self-destruct sequence that would destroy the Scub Coral if either girl would become the next Command Center. Eureka felt a sudden change in her body and, realizing her time with Renton was over, she apologized to him for their failed dream and transformed into a Coralian event. As she was transforming into the new Command Center, Eureka mentally told herself that she loves Renton and the kids more than anything and wanted to be a family with them but she was willing to sacrifice herself to save them, despite her desire to see Renton again. Enraged at losing Eureka after everything they've endured together, Renton decided to save her on his own. He begged Nirvash to awaken so it could help him reach her, and it reacted by transforming into its true form. Renton was easily able to destroy the Antibody Coralians and his desire to get to Eureka allowed him break into the Zone and find her. she was overjoyed that he came for her but told him she can't go back anymore. He replied that if she is choosing to give up being a Coralian to save the planet then he is choosing to give up being human so that he can be with her and he treasures the planet they live on because its where he met her. He gives her a flower hair clip, comments how beautiful she looks, and asks her to join him and merge with the Scub Coral, which she agrees without hesitation. They share their first kiss and activate the Second Summer of love, which creates rainbow waves that carve a heart and their names into the moon. Nirvash ejects them the Zone and tells them that the Scub Coral had found enlightenment. It also explains that half of the Scubs will be departing to another universe to avoid the Limit of Questions again and asks Eureka and Renton to set an example to the humans by living together and bring forth a new evolution (human-Coralian hybrid children) before thanking them for everything and disappearing. Relieved they are free to live a normal life, they decide to return to Bellforest and share their second kiss as they return to the planet. A year later, the family record book lists Eureka as Renton's wife and the kids as their adoptive children, confirming that Eureka and Renton got married. As the children and Axel wait for their return, Eureka and Renton are seen together near a lake, holding hands and their foreheads glowing (hers blue and his red) to symbolize their deep connection.
Eureka Seven: AO
A few years after the end of Eureka Seven, Eureka and Renton have two children together: a girl and a boy. Upon learning of her first pregnancy, Eureka and Renton were happy to be able to have their first child and were more overjoyed upon learning they were having a girl. However, they were warned that high levels of trapar concentrations would affect their child and potentially result in death. Despite their concern, they chose to carry the pregnancy to term rather than choose abortion. When Eureka was six months pregnant, they discovered that the Scub Coral was mysteriously disappearing and they began using the Gekko as part of an experiment to learn the cause. during which, a Scub Burst occurred and Eureka, with the Gekko and Nirvash, was taken to the year 2025 of an alternate universe, where she met her future son, Ao. While not knowing he is her son, Eureka and Ao bonded as she talked about her history, including her relationship with Renton and how she came from another world. Ao began asking her if her baby's father was a member of the Gekkostate and Eureka got embarrassed but confirmed it, describing Renton as "immature", a crybaby, and little hopeless" but said she still loved everything about him. Once Generation Bleu arrived to assist, Eureka was left with Rebekah and said that while she was afraid of giving birth, she was more worried of her child hating her for being born as a hybrid. Rebekah countered that Eureka chose to fall in love with Renton and have his child. After being attacked by the Japanese military and Truth, Ao helped her escape and prepared to send her back to her world via a pillar of light. Remembering when Ao first called her "mama", she asked him why and instead of telling her that she is his mother, he asked her to give birth to a healthy boy but he was shocked when she revealed that her baby is a girl. Eureka travels through the pillar of light and assumed she is saved by Renton when she encounters the Nirvash Mark I, which he was building at the time. But she was surprised to hear it was Ao piloting it and he revealed he was her son before returning her to her world.
Three months later, Eureka gave birth to their daughter and they named her Amber Thurston. At first, Amber appeared to be a healthy child, and Renton and Eureka were happy with their new family. However, they were devastated when Amber turned to stone and died at three months of age and more so when they were told to not have anymore children not that it was confirms human-Coralian hybrids are unable to live in a world with high trapar concentrations. However, they knew that Ao would be born and, still wanting to have a child of their own, they carefully planned a way to raise him a world with little to no trapar and Scub Coral, and shortly after, they conceived Ao. They decided to keep their son and raise him in the world where Eureka first met him. When Eureka was seven months pregnant, they traveled to the future of Ao's world to prepare for his birth but were attacked by Secrets. Renton sent Eureka into a pillar of light to save her and the baby while he stayed behind to destroy the Secrets and keep them from following her. Eureka refused to be separated from Renton, who insisted it was the only way to save Ao and he didn't want Eureka to kill her own kind. Arriving in the year 2012, Eureka fell from a sky above the Iwato Island, where she was rescued by Dr. Toshio Fukai, who offered her shelter. Two months later, Eureka gave birth to her and Renton's son and gave him the name she and Renton picked for him: Ao Thurston. She was feared by the island's residents for being a foreigner and having blue hair, but Toshio took her and Ao in. During her time in Iwato, she dyed her hair brown to not rouse suspicion from the residents who resented her. Eureka raised Ao for the first three years of his life and was a loving mother to him. She had his name recorded in her bracelet so that it would be used to help him pilot Nirvash and she believed he was meant to be its pilot in her absence. One day, a Scub Coral appeared along with a Secret and created massive chaos, and the American military came to take Eureka with them to stop it. Initially, Ao believed his mother was taken against her will because of how the residents despised her but it turns out that Eureka went on her own free will and, before leaving, she explained to Toshio that if she didn't go, everyone would die and Renton wouldn't be able to find her and Ao. She also decided to go because the appearance of a Scub Burst would more likely kill many people, including Ao. For most of his life, Ao wondered why his mother endured so much hate from the residents for his sake and earned it was because she made a promise to Renton to protect their son while Renton was fighting to keep them safe.
Eureka tried to remove the Quartz of a Scub Coral to destroy it until a Secret appeared and, unable to stop it with just the Nirvash Mark I, Eureka decided to take the quartz to another location of another world. Before she disappeared into a bright light, Eureka apologized to Ao for leaving him. After no trace of her, minus Nirvash, is found, everyone assumes Eureka died stopping the Scub Burst and Ao was placed in Toshio's custody. Many people in the military and politics remained interested in learning her origins, despite their distrust in her and deeming her a threat due to her connection to the Scub Coral. The Japanese military became interested in finding her and using her for their benefit due to her being an excellent IFO pilot. However, the Secret she fought before her disappearance, Truth, harbors a deep hatred for Eureka and desires to get revenge on her, and that malice was passed on to her son, Ao, after learning the boy is her child. She is referenced by Truth as being the true owner of the Nirvash mark I, and Elena Peoples mentions to Ao that she was brought from another universe by Eureka and saw multiple visions during the time-skip, such as the Gekko, Bellforest, and the Nirvash TypeZERO. She first appears in holographic form to Ao as he was fighting with Truth and she asked him to send her back to Renton, which he refused, and she informed him that something terrible will happen if he doesn't. She later appears to Naru and asks her to help Ao destroy the Scub Coral or else something bad will happen to Ao, but the girl ignored her and made Eureka disappear. Eureka later on appears to Ao again as he was fighting Truth once again and she explained the events that led to her disappearance. When Ao told her about his Quartz Gun, she said that was the weapon his father has been searching for in order to save the. Eureka appears to Elena and Maggie Kwan while looking for Ao. Ignoring her questions about Ao's whereabouts, Elena lunged at her but passed through Eureka and pleaded to be taken back to the world with the heart on the moon, much to Eureka's embarrassment. Eureka understands Elena's anger and tells the girl she is not from Eureka's world but was saved by her from a Scub Burst in 1981 and carried to a different timeline. She appears in holographic form for a last time in the second last episode just as Renton arrives in the year 2025 and the two are briefly reunited. They are happy to see each other again but Eureka warns Renton not to touch her because he wouldn't be able to due to her current condition and she apologizes to him for her sacrifice, and Renton counters that he should be apologizing. She tells him that Ao has grown into a good and energetic boy and is as honest as him and has what he seeks before she disappears.
In the final episode, after realizing the pain his parents endured following the death of his sister and sacrifices they would go to keep him alive, Ao decided to save his mother and reunite her with his father by changing her fate. He travels back to the year 2015 as she was about to disappear and they share a happy reunion. When asked by Ao how she knew it was him considering he would still be a baby at the time, Eureka replied that she remembered when he helped her back from her first trip to the past and how she learned he was her son. She asked him why he didn't tell her soon and he said she wouldn't have believed him and he knows she was pregnant with his sister back then. Renton arrives and Ao tells Eureka to go with Renton while he deals with the Secrets, which she refused, knowing it will mean she will never see her son again. Ao tells her he knows of how she and Renton destroyed a lot of Scub Corals to protect him and he blames himself for everything they've been through. Eureka counters that everything that is happened is due to her and Renton's decision to fall in love and have children and its their responsibility. Ao tells them both that he wants to repay them for sacrificing so much for him and he wants to free them from that burden because he is their son. Eureka cries against Renton's chest, who is also crying and voices his love and pride for his son. As they part ways with their son, Eureka tells Renton not to cry in front of Ao. After this, Eureka never sees her son again.
Renton is Eureka's partner and eventual husband. Starting off as one-sided love on Renton's part, to co-pilots, to love interest, to husband and wife, their relationship is the most complex in the series. When they first met, Renton was speechless and entranced by her beauty and Eureka was confused by his advances. Eureka first described Renton as immature, a crybaby, and a bit hopeless. But overall, Eureka liked Renton for his amusing and good-natured personality. Unlike how most of the Gekko crew treated her with respect for being Nirvash's pilot, Renton sought to help her overcome her struggles as much as possible after she confided in him about her past misdeeds and her desire to atone for them, and he often told her she can become a better person by accepting changes. As Renton began to understand the effect his presence had on Eureka, he vowed to protect her. Because of this, his infatuation and admiration for her turned into genuine affection and care, allowing him to truly fall in love with her. Eureka didn't reciprocate his feelings because of her lack of understanding what love meant, although she appreciated his friendship and she found him to be the most interesting person she ever met. She also credited his presence on the Gekko for allowing everyone to have fun and be more open with one another. Their relationship is almost brokwn due to Eureka's jealousy at Renton for supposedly being a better pilot than her and Renton, believing she grew to hate him, left the Gekko. During his absence, she realized her feelings for him and how she wants to be with him forever, allowing them to reconcile and begin a relationship. She becomes very devoted to Renton and takes most things he says to heart, and looks to him for help. She becomes determined to make him happy with her and makes is known that she will stay with him forever. Her love for him has grown so strong to where she can't bear to be apart from him and she quickly envisions herself marrying him and having a family with him. It was because of their deep love that they are able to perform many impossibles, like going to Earth and saving the planet from the Limit of Questions. Eureka gets worried over her identity as a Coralian and feared Renton would one day leave her, despite him assuring her the contrary; after getting green spots and wings, Renton accepting them caused Eureka to tell Renton how much she loved him for the first time. At the end, they would go on to marry, adopt the kids, and have two children together. Despite everything that's happened, Eureka insists she doesn't regret falling in love with Renton.
Maurice, Maeter, and Linck
They are Eureka's adopted children and, next to Renton and her biological children, are her most beloved people. Orphaned during the SOF attack on Ciudades del Cielo, Eureka discovered them crying beneath a pile of corpses. Horrified of what she'd done, Eureka took them in and quit the SOF with Holland. Eureka loves the children but due to her lack of knowledge of raising children, she often spoiled them and rarely, if ever, disciplined them until Renton teaches her what she needs to do to be a parent. The kids tend to misunderstand the way Eureka expresses her feelings and often worry that it will mean she will abandon them. They love Eureka very much and are protective of her, which causes them to get suspicious of Renton at first. After a while, they warm up to him a bit and accept him as part of their family.