I know my younger brother's wife, Rin, is cheating, but I can't bring myself to tell him. The reason is, I've also had a relationship with her. Despite being consumed by guilt, I gradually begin to resist her advances. In response, she starts provoking me more intensely—flashing me while masturbating, bringing her lovers home and having sex right in front of me. The story unfolds as the protagonist struggles between his own desires and moral conscience.