Tomomi Yamanaka is a first-year student at Hayashigakuin School, known as Rinin Academy, celebrated as one of the institution's most beautiful students. Her appearance features distinctive long, straight blue hair with a middle part, green eyes, and a pale complexion typical of her teenage years. She consistently wears a sailor-style school uniform with a pleated skirt, over-the-knee socks, and a ribbon hair tie.

Academically and athletically gifted, Tomomi represents her school as a sports gymnast competing at the prefectural level. Her athletic excellence and striking looks secure her features in sports idol magazines. She maintains a cautious romantic relationship with Tagami (Kenji), a prominent baseball team member acclaimed for his regional competition performances. Her older brother Satoshi, a fellow baseball teammate, facilitates their discreet encounters in secluded school areas.

Tomomi's brother Satoshi harbors inappropriate fixations, including installing hidden cameras in her bathroom. He colludes with the Rinkan Club—a group orchestrating non-consensual acts under ritual pretenses—by manipulating her nomination as a "priestess" to target her. This leads to her assault near the baseball field, where a baseball bat is used to forcibly take her virginity, an experience she had reserved for her boyfriend.

Her ordeal culminates in the school gymnasium with a further assault witnessed by Tagami. Post-incident, the Rinkan Club formally designates her as their priestess. Her story concludes with permanent integration into the club's rituals, tracing a path from acclaimed student-athlete to enduring victim of their exploitation. These events remain consistent across the original visual novel and its adaptations.