Tomomi Shirakawa is a Japanese high school student at Shirakawa Academy, wielding significant influence as the granddaughter of the institution's board chairman. She leverages this privileged position to manipulate situations according to her desires.

Driven by petty jealousy, particularly disliking the idea of sharing top status on the rhythmic gymnastics team, Tomomi targets specific female club members to "mess up." She discovers gym teacher Nikusuke Toguro's secret "Dark Rhythmic Gymnastics" regimen, a brutal system focused on humiliation and forced training. Instead of reporting it, she blackmails Nikusuke into collaborating, using the plan against the girls she resents.

Physically characterized by her beauty, Tomomi often wears provocative clothing emphasizing features like her breasts and buttocks. Her personality exhibits entitlement, sadism, and cowardice. She orchestrates the forced participation of other students in Nikusuke's degrading initiation ceremonies, which include electric torture and sexual humiliation, demonstrating her cruel and manipulative nature while exempting herself.

Tomomi's downfall occurs when Nikusuke turns on her, subjecting her to the same brutal initiation ceremony. She endures physical and sexual violence, electric torture, and degradation, displaying intense fear, attempting to flee, and suffering a complete psychological breakdown. This crumbles her earlier arrogance and perceived invincibility, marking a shift from perpetrator to victim.

Her narrative concludes with an ambiguous fate, implied to involve continued subjugation under Nikusuke, potential pregnancy, and the loss of her former status and autonomy.