Runmaru is a character from Jibaku-kun (as known Bucky: The Incredible Kid or Bucky: Searching for World 0) series, a creation of Ami Shibata. He is the older brother of ChaCha and the seventh G.C. of Seteras.
Runmaru is a very skilled ninja and experts in ninjutsu as well as the older brother of ChaCha. When his sister was taken hostage by the Toad Lord, Runmaru is unable to touch the monster due to his sister being held hostage as well as she becomes their slave and the Toad Lord is controlling the region of Seteras. By the time, Toad Lord and his assistant are putting his sister in slavery, Runmaru is observing them and he has no choice but to watch.
During Episode 18 when Bucky and the group are travelling to their region, Like other Great Children, Runmaru also heard of Hail's declaration of taking Bucky and the group as Trouble Kids. As Bucky attempts to stop the giant golden fish Trouble Monster, Runmaru intervenes them to fight the monster as he throws his spirit, Rekka to electrocute the monster with a Thunder Ball technique to knock it down. Bucky also notices him for being a G.C. while Pinky also recognizes his outfit for being a ninja. Runmaru finally intoduces himself to the group and he tells them that he needs his help to rescue his sister, ChaCha from the Toad Lord which Bucky refuses. Due to this, Runmaru attacks him by throwing Rekka with a Wind Ball technique. This prompts Bucky to retaliate and unleashes his Powerful Wave to make their techniques collided in explosion making their fight in an equal match. Runmaru creates a strong wind technique as Bucky tries to defend himself as the strong winds manage to scratch him in all parts of his body. However, Bucky manages to use his Supremacy technique to find the direct target as he throws Jibac on the ground in explosion to destroy the strong winds. Runmaru discovers his technique which he remembers that he was taught this technique by Master Funen. Their fight becomes halted when Kai and Pinky arrive to see Bucky as Runmaru escapes the scene.
Back at his home, Runmaru gets his worn karate gi that he previously wore during his training with Master Funen and seeing that Bucky learns this ability from him as well. By the time Bucky is watching both Pinky and Kai are attempting to rescue his sister, Runmaru arrives behind him which both men wanted to continue their fight. Both men are now seen ready to fight on the roof. Bucky realizes how Runmaru is unable to save his sister from being hostage which is a shock to him as he scolds him for being a coward which Runmaru angrily bursts out of his reasons which Bucky becomes discourage to him while walking away. Runmaru stops him which Bucky tells him that he has to learn how to take things seriously in saving his sister. Runmaru gets his katana from his back and angrily attempts to attack Bucky which Bucky dodges his sword attacks as Preme watches them fighting. When Pinky and Kai are rescuing his sister, The Toad Lord manages to take her away by pulling his purple tongue after seeing their attempts. Runmaru quickly manages to get through Toad Lord's castle which Bucky becomes angered by this as he follows him. However, Funen in his mole-like octopus form has been observing the turn of the events. Runmaru now confronts the Toad Lord along with Pinky and Kai as he attempts to rescue his sister as the Toad Lord spits with red acid goo causing him to dodge. Knowing of his attempts are futile, Bucky manages to knock the Toad Lord with a single kick to his head and Runmaru quickly rescues his sister ChaCha.
This angers the Toad Lord for hurting him as he hits Bucky with his purple tongue as Bucky dodges and he throws his spirit Jibac at him in explosion. ChaCha now convinces Runmaru to help them as the latter refuses due to his values as a ninja as Bucky manages to defeat the Toad Lord with a Powerful Wave. Bucky now tells Runmaru that a G.C. is supposed to be serious in fighting against trouble monsters and it was a main example in how to defeat the Toad Lord with a single Powerful Wave which angers Runmaru from his scolding. However, he senses that his former master, Funen has been watching them all along in his mole-like octopus form which he and Kai easily recognizes him. Funen tells him that the most important thing is to go to his own path rather than the rules. However, The Toad Lord is still alive and he transforms into a giant toad while being engulfed into giant tornado which Runmaru tries to protect his sister from it. The Toad Lord becomes a giant Godzilla-like toad much to everyone's shock. Runmaru tells them that Funen can fight the monster. Buckjy attempts to throw Jibac in explosion but is no effect as its smoke got eaten by the Toad Lord until his second attempt where he tries to punch him in mid-air but can't reach it due to its size as he falls deeper in the edge only to be save by Funen who is now in his gigantic state while holding at Bucky's feet with his long strand of mole whiskers which both Runmaru and Kai recognize him as both Funen and Toad are ready to clash into a gigantic monstrous fight.
Both Funen and Toad Lord are equally matched when they pummel each other with both his purple tongue and his mole whiskers while they destroy his own castle as Bucky and the group cheers him. Toad Lord manages to knock Funen down as he was release from his short blue basket while showing his mole-like octopus form in a gigantic state. Funen eventually manages to defeat the Toad Lord by spinning himself like a drill torpedo to hit him with his stomach using the Supremacy technique. After the incident where Preme eats the essence of Slash's Poison of Awakening on the Toad Lord which reverts him back to a normal toad. Then, Bucky and the group finally bid farewell to Runmaru and his sister for their travels and Runmaru finally accepts Bucky's words after telling him that Hail was the one who cause all the trouble. With that, Runmaru gets the paper with a sketch of Bucky due to Hail's declaration as he crushes it knowing that never forgives Hail for causing all the trouble in his region and his dirty deeds.
During Episode 25, Runmaru is protecting his region from the shadow versions of Slash before being frozen in solid by Spaak's sister, The Princess under Slash's possession and being freed from being frozen as Bucky defeats Slash in the second battle against him. He was last seen among with fellow Great Children in the final battle against Slash.
Runmaru has a long dark gray hair with long layered fringes in each side of his head and is pulled down in a low ponytail and brown eyes.
His primary appearance is a black sleeveless traditional ninja garb with a yellow sleeveless mesh undershirt, matching ninja pants with a yellow karate belt to his waist and a traditional ninja sandals. He also has a katana on his back and has black wristbands on both of his wrists.
During his training with Master Funen in his flashback, he was seen wearing a white sleeveless karate garb, and white pants with a black belt to his waist.
Runmaru is described as a bold and emotional person who wanted to save his sister from being hostage by the Toad Lord but is unable to do so. He is also being stubborn due to the values as a ninja as his own rules. Despite this, he becomes calm and respectful towards Master Funen after he watches them fighting the Toad Lord and being scolded by Bucky. Runmaru is a somewhat a stereotypical ninja who runs fasts and jumps faster in the roof which it angers Bucky from his speed and agility as a ninja.
Runmaru's abilities is based on ninjutsu and he mostly uses his Spirit to make balls of elements. He also uses his katana as his main weapon.
Thunder Ball: Runmaru throws his spirit Rekka to make a purple lightning to electrocute his enemies to knock them down. This ability is used to exterminate the golden fish trouble monster.
Wind Ball: Runmaru throws his spirit Rekka to make a strong winds towards his enemy. This is used to attack Bucky as the latter retaliates this ability with his Powerful Wave technique.
Wind Storm: Runmaru summons strong winds by chanting them towards his enemy as the winds itself manage to hit the enemy several times while being engulfed by it. This is ability is used to hit Bucky as the latter manages to destroy it due to the usage of his Supremacy technique.
Sword Slash: Runmaru uses his katana as his main weapon which he slashes his opponent with his katana. This is used to attack Bucky with his katana after the latter tells him to act serious to rescue his sister.
- Runmaru's region in Seteras is based on the Feudal era in Japan.
- His fighting style Ninjutsu is based on the game Final Fantasy Tactics.
- In the Japanese version of the anime, he is voiced by Kenichi Suzumura.