Yukino Hongou is a teenage girl with long maroon hair reaching her waist, blue eyes, and a slim figure. She typically wears a sailor-style school uniform with a neckerchief, hairpin, and torn pantyhose. Yukino lives in an isolated mansion with her mother, Ruriko Hongou, and younger sister, Ai Hongou. The family has no contact with the outside world, lacking even a telephone. Yukino endures brutal rituals orchestrated by cult enforcer Mushizou under her mother's direction. These rituals include repeated sexual violations and forced intercourse with a bull, culminating in her pregnancy and the birth of a deformed entity known as a Kudan. Her existence involves daily torture and exploitation in obscene ceremonies tied to a cult worshipping "Oshiro-sama." Yukino passively endures these acts, rarely resisting, and silently prays for rescue. She experiences prophetic dreams, including one featuring detective Kyousuke Mibuu before his arrival. When Kyousuke appears to investigate, Yukino initially tries to send him away, fearing for his safety though secretly hoping he might save her. Following her mother's sacrificial death in a fire, Yukino escapes the mansion with Kyousuke and Ai. She develops a close bond with Kyousuke, becoming his partner. This relationship creates tension with Kyousuke's assistant, Momoko Momono, who grows jealous of their connection. Yukino remains largely unaware of Momoko's subsequent suffering. Yukino's story concludes differently across various endings: - In one outcome, she gives birth to the Kudan after prolonged rituals. Kyousuke is killed by Mushizou and reincarnated into the Kudan's body, leading to the mansion's collapse and their entrapment. - Another ending depicts her participation in sexual rituals with multiple men, including Kyousuke, before witnessing Kyousuke's execution by Mushizou. - A final ending reveals the rituals were part of alien experiments manipulating human perception of time and cause-and-effect. Yukino's mother orchestrated the torture due to jealousy over Yukino replacing her as shrine maiden. After escaping the burning mansion with Kyousuke, Yukino learns of her mother's betrayal, which devastates her. She becomes Kyousuke's detective assistant and builds a life with him.