Ichibanboshi witnessed a masked samurai with a glowing purple sword slaughter his parents and younger brother in his youth, scarring him with an enduring hatred for samurai and igniting a ruthless quest for vengeance. His relentless hunt for masked adversaries culminated in imprisonment and a death sentence after he assaulted one such foe.

Spared execution by joining a squad of condemned criminals replacing fallen Shinsengumi captains, he adopted Isami Kondō’s identity, emerging as the substitute unit’s impulsive yet effective leader. Unkempt red hair and a defiant pompadour defined his look, while his katana, Kotetsu, sometimes pulsed with light tied to the spirits of the original Shinsengumi.

Clashing with allies like the disciplined assassin Sakuya over leadership tactics, his vendetta intensified upon discovering Rashōmaru—leader of the Masked Demons—was his brother Tsukito. Separated during their family’s massacre, Tsukito had been manipulated into killing their mother and groomed by the Demons, fracturing their bond further.

Struggling to reconcile vengeance with duty, Ichibanboshi gradually tempered his rage, cooperating with the substitute Shinsengumi during missions such as safeguarding scholar Shōzan Sakuma and countering threats like the Dark Slayers. His journey wove loyalty, redemption, and the ghosts of his past into a fragile path toward unity.