Ninja Fight is episode 13b of season two of Hero: 108.
At Rabbit Castle, a lone sentry patrols by night, hopping back and forth. When he hears a knocking sound, he turns to the thick castle door, now beginning to quake, with his sword drawn. He sees a green arm smash through the sturdy wood and cleave through the chain holding the door closed. The sentry prepares for a defense, but many more such arms begin spring from the hole, and while he holds them at bay with his sword, he is defeated when one grabs a doorpost and throws it at him.
The door begins to bulge and ultimately flies off its hinges, and the sentry is able to see his assailants: the mantis army. He rights himself, grabs his sword, and prepares to repel them, but is overwhelmed and disarmed by their sheer numbers before he can even land a blow. As the sentry is held and stretched painfully by the mantis warriors, another rabbit appears, whom the sentry recognizes as Spotter. Spotter, with excellent grasp of human language, taunts him.
Realizing the threat, many more rabbits lead an assault, now armed with jumpropes. The mantis, however, make short work of them, lifting them and spinning them until they can no longer fight. The rabbits are then dropped in a heap and tied up. Another rabbit tries to flee, but is pinned to the wall with carrots fired by Spotter's mantis body armor. Asked what he wants, Spotter replies that he wants "everything, starting with Rabbit Castle." He demands a one-on-one battle with the Rabbit King, Jumpy Ghostface.
Meanwhile, at Big Green, First Squad is finishing a meal. Jumpy is preparing to eat a chocolate treat, but finds it snatched by Beetle King. Jumpy confronts the beetles, and learns that Beetle King had not thought Big Green would have given him the chocolate, which he used to motivate his troops, had he simply asked for it. Jumpy also learns that the beetle army severely lacks teamwork skills.
In First Squad's briefing room, a rabbit tells of Spotter's arrival at Rabbit Castle, that Jumpy must face him alone, and that the mercenary mantis army fights for him. Lin Chung assumes that First Squad will face Spotter together, but Jumpy asserts that he must fight the personal battle alone.
In Rabbit Castle, a fightened rabbit approaches Spotter with a tray of carrots. Spotter, infuriated that the slices are too thick, stands over the scared rabbit, not realizing that a rabbit is rappelling down behind him. This rabbit, nearly identical to Jumpy Ghostface in appearance, is taken by Spotter to be the genuine Rabbit King, and the two begin to duel. Spotter gains the upper hand, however, and attempts to force his foe to declare that he, Spotter, will henceforth be the rabbit king. His pinned foe, however, makes a different statement: that he is Mighty Ray.
Mighty Ray's cover now blown, Lin Chung and Mystique Sonia enter the battle as well. Mighty Ray removes his rabbit disguise, and prepare for an attack with his eyeballs. The battle is ended before it can begin, however, because Spotter still holds the rabbit civilians hostage.
Suddenly, Jumpy arrives, wearing beetle armor, clearly mad that First Squad did not listen to him. Spotter attempts to strike him but fails to lay a blow on the nimble Jumpy. Jumpy flies into the air with the help of his beetle armor, the comes down to deliver repeated kicks to Spotter's face. Yet still confident that he will be victorious, Spotter commands the mantis army to destroy First Squad. Even as First Squad takes the upper hand, Spotter calls for reinforcements.
It is at this time that another army appears: the beetles, led by Beetle King. The beetles face off with the mantis soldiers, while Jumpy and Spotter travel deeper into the castle. Jumpy offers mercy to Spotter, but the vengeful rabbit beleives they are sworn enemies. He claims that the old rabbit king made them so, when he picked Jumpy as his successor. Spotter could not tolerate being second in charge and had left. The two fight more, but neither bests the other. However, Spotter then attempts to return to the larger battle, where he may attack Jumpy's friends. He begins flying toward Sonia, prompting Jumpy to save her. He flies toward her even faster, using his beetle armor to block Spotter, though the armor is shattered in the process.
Seeing Jumpy fall, Spotter is convinced that he has won. Jumpy, however, kicks him from the ground, knocking him back. Spotter charges him, but Jumpy uses his jumprope; when Spotter hits it, he is tied up. Spotter is defeated.
Lin Chung cuts free the rabbits, then advises that the mantis troops flee, which they do. Mighty Ray tries to convince Beetle King to make him armor like Jumpy's, but Beetle King instead proposes making him a muzzle to keep his mouth shut.
- Beetle King can now speak human language, something he had heretofore not done.
- It is revealed that Jumpy won his kingship with his rope skills.
- The statues in Rabbit Castle appear to depict the rabbit king who precede Jumpy.
- The door to Rabbit Castle has two bars when a mantis reaches up to grab one. When the mantis warriors destroy the door, the one that was not thrown is missing.
- In some scenes, the legs on Jumpy's armor touch, while in others, they do not.