Izou fought as a samurai defending Shogun Yoshinobu Tokugawa at Edo Castle during the Shogunate's fall. Betrayal by his superior, Kōketsu, cost him his right eye, stripping him of purpose and leaving him emotionally detached, merely existing. After the Meiji Restoration, he took employment as a bodyguard at a Kyoto brothel. His duties included confining a disruptive elf girl, Sonya. His initial indifference shifted through interactions with Chihaya, a high-ranking courtesan and secret elf who noticed his light blue aura and received small kindnesses like an English vocabulary book.

A violent raid targeting elf captives forced Izou to reclaim his katana and fight. He witnessed Chihaya die protecting Sonya, an event rekindling his sense of duty. He escaped with Sonya and Raiden, an orc defector. Izou bears battle scars, most notably over his rain-sensitive right eye. He carries a katana and wears traditional attire. His aura visibly shifts to black during intense rage, triggered by memories of Kōketsu's betrayal or combat.

Initially distrustful of Raiden, Izou gradually formed a bond through shared combat and journey conversations. Their mission became escorting Sonya and Chihaya's powerful wand to elf territory in Hakodate while evading the Inferni organization. Protecting Sonya restored Izou's purpose. He ultimately discarded the wand into the ocean to prevent its misuse, rejecting magical shortcuts and affirming human agency in resolving conflicts, marking his transformation from a disillusioned ronin to a self-determined guardian.