For a long time, Tsukasa had viewed his sister-in-law Ai as a sexual object. One day, he accidentally witnesses Ai in the act of adultery. The shock pushes Tsukasa's restraint to its limit, and unable to suppress his own desires any longer, he summons Ai and threatens to claim her body unless she submits—keeping her affair a secret from her husband, his older brother. This scenario deeply explores the inner turmoil of characters torn between desire and morality, portraying complex relationships and emotional conflict.