The boyhood rival of Miyamoto Usagi, the two of them competed for everything. Kenichi was always resentful of Usagi for being better at seemingly everything, even if only fractionally so.

Kenichi went to the Dogora fencing school while scorning Usagi for taking up with Katsuichi, the renegade sensei. Kenichi left the Dogora school after his tournament defeat at the hands of his old rival, and eventually returned to the village.

There he stayed while Usagi went to serve Lord Mifune, taking the hand of Usagi's childhood sweetheart Mariko, even though she was with Usagi's child. He became the headman of the village when Usagi's father was killed by Lord Hikiji before the battle at Adachigahara. Kenichi has done well as the head of his village, fending off attacks from the Mogura Ninja, the bandits led by the demonic Jei, and numerous other threats, as well as raising the boy Jotaro as his own son.

He still holds a grudge against Miyamoto Usagi, however he is, if nothing else, an honourable samurai.