Yukari Tatsumiya is a young woman with innate psychic abilities, targeted by antagonist Yasunori Kato for exploitation as a medium to awaken Taira no Masakado's destructive spirit and destroy Tokyo. She belongs to the Tatsumiya family and has a brother named Yoichiro Tatsumiya.

In 1908, Kato kidnaps Yukari and implants a parasitic spirit (fukuchu-mushi) to control her, intending to channel Masakado's power through her body. When initial attempts to invoke Masakado fail, Kato employs dark magic to forcibly impregnate Yukari, aiming to produce a child with amplified spiritual potential. After allies of onmyoji Yasumasa Hirai rescue Yukari, she returns to her family, where her brother Yoichiro sexually assaults her in an incestuous act.

Yukari gives birth to a daughter, Yukiko Tatsumiya, who inherits heightened spiritual capabilities. Yukari's active role diminishes, shifting the narrative focus to Yukiko as Kato's new target a decade later. By 1927, Yukari resides passively with the Tatsumiya family. Kato later possesses her body to exploit her residual connection to Yukiko's powers, attempting to amplify an apocalyptic event involving the celestial Firmament Dragon. Yukari survives these events but remains a secondary figure, her personal arc unresolved beyond her function as a victim and catalyst.

Her character exemplifies repeated victimization, advancing the plot through her suffering and the legacy of her abilities passed to her daughter.