Yuna, a childless married woman, decides to bring her nephew Koichi into her company as her successor. Captivated by his pure and cheerful personality, Yuna gradually develops romantic feelings for him. Koichi finds himself emotionally shaken by his aunt's bold advances, consumed by these forbidden emotions. One day, Yuna approaches him nearly naked, seducing him with explicit intent. Overwhelmed by her lewd appearance and aggressive actions, Koichi finally loses control and gives in.