|“||Muwahaha... I was the only one that you thought would never turn on you, wasn't I? Mr. King... Joker was the last of your loyal subordinates. Actually, he was only your Wizard so he could fulfill his own Purpose... You have been surrounded by traitors from the very beginning. There was Jack, Queen Tia, and of course, myself... Goodbye, Mr. King... You will pay for your sins in the bowels of your own Noise.||„|
|~ Heartless, revealing to be a spy for the WAXA.|
|“||The world is counting on you.||„|
|~ Heartless to Geo.|
Heartless is a supporting protagonist in the Mega Man Star Force 3. She is a member of the Dealers, and is a representation of the suit of Hearts.
Throughout most of the story, she poses as an antagonist and functions as Mr. King's right-hand woman, speaking for him and arranging missions for the Dealer's members. However, she revealed to a double agent, working in hopes of finding Kelvin Stelar, father of the main character Geo Stelar.
She seems cold and emotionless girl at first, but is quite cunning, patient, supportive, kind and loving person. She also shown to be a very caring, as she is willing to found Kelvin. She also very intelligent, when she trapped Mr. King during her betrayal. She is willing to stop everyone who desires to harm earth or the innocence.
As she appears to be a very attractive woman, who wears a black dress that has diamond hearts on it, also has short pink hair. Her eyes are appear to be dark blue. She also wearing dark pink leggings and black heels
A few years before the game's timeline, Mr. King was researching ways in how to achieve dominance over Earth when he then stumbled upon Meteor G; at the same time, he met Heartless who was searching for Kelvin Stelar and who had also found about the celestial body. Wanting to get close to Meteor G herself, Heartless contacted Mr. King and became his right-hand lady. He also was able to secure Mu Technology for himself.
Joker first appears beside Jack and Queen Tia, as they give a report on Diamond Ice's Crimson generation. King spends a few moments discussing his goal, and Jack, increasingly agitated, starts demanding to fight Mega Man. Joker chastises him for being quite rude to Mr. King, which prompts Jack to respond directly to him, though it's not until Heartless admonishes him that he returns to his place. Following some criticism of Jack's behavior, Mr. King has Heartless dispense his orders.
Heartless reveals that Mr. King has received a large amount of supportive emails, all of them full of good reception at his charitable work. Mr. King has Heartless start the analysis process of Mega Man's data to finish the Ultimate Weapon.
Heartless informs Mr. King of Tia's defeat but since the attack led by her was successful in destroying most of WAZA and the Satella Police, he refuses to rescue Tia. Heartless asks Mr. King what should be done about Jack since he hasn't behaving as himself. Mr. King reaffirms his suspicions and has Heartless get rid of him since both Tia and Jack were pawns from the start and that Jack is of little use to him with his sister gone, knowing that it will make Jack even more reckless and precise. However before he can finish, he states that Jack could still be of some use and wonders whether he has some parental feelings left. Mr. King just tells Heartless to let Jack do as he pleases.
Heartless informs Mr. King of Jack's insubordination which angers Mr. King but considers to make the best out of the current situation. Heartless suggests rescuing the siblings since they were in charge of the Crimson collection but Joker suggests otherwise as he has an idea of his own.
Mr. King merely awaits in his chambers while the Satella Police along with Mega Man and Harp Note decide to invade the Dealer's base. He is witness to Acid Ace's defeat at the hands of Joker. Mega Man appears and confronts Joker, so Mr. King allows Joker to go as wild as he can be, and to reveal his true form. Mr. King then plays a betting game with Heartless on who will win the battle.
Mr. King however considers Ace to be a superb joke and has Heartless summon a card-shaped platform to have them hover over the rest, as Mr. King looks at them and believes them worthless ants. Mr. King has a deep laughter at the belief the two have that he is truly defeated. He then reveals his trump card and has Joker self-destruct. While he retreats high up on his platform with Heartless.
Once the explosion is averted by Acid Ace albeit seemingly at the cost of his own life, Mr. King is ruthlessly overjoyed at Joker's sacrifice since it provided him with a massive amount of Crimson. Mr. King is delighted at Ace's demise believing him the proper outcome for his betrayal. Heartless merely remains silent at Mr. King's foul remarks.
Mr. King and Heartless decide to settle themselves at their Orbital Base placed 50 miles above the Earth surface, putting them in the mesosphere. Heartless reveals to Mr. King that the Orbital Base has full access to Meteor G thanks to the Crimson left behind by Joker.
Heartless says that it is impossible for Meteor G to deny Mr. King's orders at this point, therefore he concludes that a third party outside of WAZA is interfering. He wonders about who this party could be to wait at the last moment to strike at him and orders Heartless to look into the matter.
Heartless provides new information to Mr. King that several world leaders are still debating whether to submit or not. Mr. King believes them to be idiots who still cannot realize they cannot hope to defeat him so long as he controls Meteor G, and to let them debate so they find for themselves how helpless they are. Mr. King asks Heartless how the information about the third party is going but Heartless is unable to find any leads. Mr. King is enraged at Heartless incompetence and demands that she finishes by the next day or she will be punished. His previous subordinates, Tia and Jack enter the Orbital Base and confront him in their EM Wave Change forms. Both Mr. King and Heartless are surprised to see the siblings, but they remark to not be taken lightly. Mr. King believes them to be the third party, but the siblings have no idea what he talks about. The siblings reveal they were never loyal to Mr. King at all and they were waiting the moment Joker was out of the picture with himself in control of Meteor G so as to take everything from him. Mr. King once more attempts to use sentimental leverage to win over them, but it falls on deaf ears, since the siblings are more than aware that his benevolent persona was fake and that he sent several children like themselves to commit crimes for his sake with none of them coming back and without knowing the truth.
Mr. King without any remorse merely claims that thanks to his aid they were able to live that much in the first place. The siblings uttering their profound disgust and hatred at their foster parent decide to take revenge on the behalf of those children and themselves. Mr. King merely looks at them with disdain and uses a special Noise frequency to cancel their EM Wave Change and has them captured with energy rings. He explains that everything in the facility is under his control and mocks the siblings for their weakness. As he is about to punish them the capture ceases to be. Surprised Mr. King asks Heartless to explain what is happening, so she explains that it was she who cancelled the attack on them. Enraged, Mr. King demands an explanation and Heartless reveals the truth, that she was never loyal to Mr. King either and that since King relied on Joker who was a Wizard that Mr. King was surrounded by traitors since the very beginning. Disgusted at the betrayal of his second in command, Mr. King attempts to attack her, but it is futile as Heartless has him swallowed in a Noise Wave and leaves him to die in the radiation.
With MegaMan as their only hope, Heartless gives Geo all the information she had, and waits on Earth along with the rest of the cast. Hope Stelar claims that she and Heartless were once friends
Back at WAZA when the organization is planning how to stop Meteor G, King reveals himself to the party coming out of a Noise Wave. Heartless is left speechless at his survival since a human could not survive in a Noise Wave for long. He reveals that he has become an EM being by using Joker's program. With his "feelings hurt" at Heartless' betrayal, he attempts to kill her by shooting beams from his platform but Mega Man blocks them in time.
- Hope claims that she and Heartless were once friends.