"Serika Kozuki starts as a shy and insecure student, her frustration and envy toward classmate Shion Asahina's perceived violin superiority driving her to seek private lessons from teacher Akio Yashiro. Yashiro manipulates her with a disturbing premise: true violin mastery requires sexual arousal. Their lessons descend into exploitation under this pretext. Gradually, Serika transforms from student to willing accomplice, adopting Yashiro's methods of control and cruelty. She begins to derive pleasure from harassing and humiliating fellow students, shedding her initial vulnerability for active participation in harm. This arc traces a descent into complicity, marked by lost inhibitions and an embrace of manipulation as power, framed as a direct consequence of Yashiro's psychological and sexual coercion. Serika becomes entrenched within the cycle of abuse she perpetuates."