Tonoin Kei, a musical genius with extensive conducting expertise, becomes conductor of an amateur orchestra primarily to pursue concertmaster Morimura Yuuki—a music teacher and violinist—due to intense romantic fixation. Though his strict leadership elevates the orchestra's performances and earns members' admiration, Kei exhibits manipulative personal conduct, engineering scenarios to isolate Yuuki, such as stealing his violin to lure him home.

During a non-consensual sexual encounter at Kei's residence, he forces himself on Yuuki. Discovering this is Yuuki's first experience with a man, Kei expresses remorse, confesses love, and reveals Yuuki's longtime crush, flutist Kawashima Natsuko, does not reciprocate. Yuuki flees, accidentally falling down stairs and sustaining injuries. Kei nurses him through recovery, displaying genuine devotion.

Post-recovery, Kei battles uncontrollable urges toward Yuuki, persisting with advances despite promises to stop. He forcibly takes Yuuki to back rooms during orchestra breaks for physical contact. His obsession transcends professional boundaries, compelling him to abandon circumstances and search extensively if Yuuki disappears.

Kei's storyline centers on duality: pressuring Yuuki to refine violin skills professionally while relentlessly pursuing him romantically and physically. Their complex relationship evolves amid these tensions, with Kei vacillating between authentic care and harmful actions fueled by obsession.