Ryuudou Yukiatsu hails from a Hatamoto samurai family but abandoned his home twenty-five years before the main events, following a transformative encounter in the "Other World." He vanished at age fifteen and reappeared one year later, though subjectively only an instant had passed for him. This experience rendered him unable to appreciate human food and environments, fueling a profound dissatisfaction with the normal world. His time in the Other World bestowed Ayagami, the power to discern beings' true names and manifest them as weapons against supernatural entities known as Yōi. This ability made him a vital asset to the demon-hunting group Bansha Aratamesho, the Ayashi.

Returning from the Other World initially reckless, Yukiatsu lived as a ronin and bodyguard, engaging in brawls, gambling, and harassment. Fifteen years prior to the series, a confrontation forced him to kill his friend Kumoshichi in self-defense, an event so traumatic he repressed the memory. Unconsciously, he later summoned a Yōi bearing Kumoshichi's likeness. This guilt contributed to his life as a drifter, a "floater," marked by execution warrants issued after twice escaping vagrant camps; tattoos on his arm and shoulder remained as permanent marks from these incarcerations.

Recruited by the Ayashi after defending a woman and child from a Yōi, he confronted his painful past while battling Edo-period supernatural incursions. His perpetual outsider status cultivated deep empathy for societal outcasts, including foreigners and the marginalized, shaping his interactions and moral choices. Wielding Ayagami demanded he balance his rejection of the Other World against his duty to protect humanity.

In the OVA *Ayashi Divine Comedy*, set six months after the main series, Yukiatsu reunited with the Ayashi to confront a new menace and conspiracy threatening both his fate and the group's survival. This journey involved deeper exploration of his connection to the Other World and the consequences of his abilities.