Sueharu Maru has been best friends since childhood with Hozumino High School"s most popular girl, Kuroha Shida. Charming, vivacious, and caring, Kuroha embodies the ideal older‑sister persona that everyone admires. Boys line up at her feet, pleading to be near her, and she always smiles kindly. Their friendship had weathered every school event, from exams to festivals. Still, when she confesses to Sueharu one day, he instantly rejects her; he cannot see her that way. Instead, his heart already belongs to the school idol and celebrated author Shirokusa Kachi.
After a chance encounter, Sueharu thinks he might win over Kachi, only to discover she already has a boyfriend. Devastated, he ponders what might have been and feels his dreams crumble. Sueharu's heart thudded as he imagined a future with Kachi. Then Kuroha proposes: "Let"s take revenge."
