Hakushu Murasame, a celestial entity, descended to Earth in 1908 within a crystallized meteorite that crashed into Siberia’s Eastern Taiga. Observed by Valery Kaminski—who absorbed the meteor’s energy—she vanished before resurfacing in Japan. Her enigmatic origins hint at a turbulent past intertwined with human-demon wars, as evidenced by her history with the demon Oboro. He recalls their former alliance in slaughtering humans, a partnership she severed by killing him during their final clash.

A master swordswoman, Hakushu mentors Sakura Amamiya in bladecraft while managing a Tokyo orphanage sheltering demon children, advocating for interspecies harmony. By night, she dons a white musketeer mask and cape as the vigilante White Cape, thwarting threats like the mechanized Black Cape and confronting Klara M. Ruzhkova—a girl tied to the dissolved Moscow Combat Revue. Their dynamic shifts between protector and strategist: Hakushu rescues Klara from abduction, employs her as bait, and interacts with her at the orphanage, where Klara detects an uncanny familiarity in her combat style.

Though outwardly stoic, Hakushu harbors a playful streak, weaving puns into conversation that bewilder allies and foes alike. Her dual identity stays concealed despite unmasked speech and replicated techniques. The anime expands her role, depicting covert aid to the Flower Division mid-battle, orchestrating Klara’s safety, and unveiling her non-human nature through winged transformations. Her ties to Natalia Ruzhkova, Klara’s guardian, remain undefined yet evident.

Driven to shield Tokyo’s marginalized—whether through orphanage care or vigilantism—Hakushu navigates human-demon tensions with impartiality. She confronts adversaries like Oboro and Black Cape decisively, balancing loyalty to Sakura and the Flower Division with indirect guidance, her celestial legacy and obscured humanity never undermining her resolve to nurture and defend.