After losing her husband, Sumire was overwhelmed by loneliness. Her daughter and son-in-law, worried about her, spent every weekend with her, helping her slowly regain some hope. Behind closed doors, however, she secretly satisfied her sexual desires by masturbating while watching the couple's intimate moments. One day, when they planned to go out together, her daughter had to cancel due to work, leaving Sumire alone with her son-in-law. That night, as a gesture of gratitude, Sumire began giving him a massage. The way she touched him made it impossible for him to resist—he naturally became aroused and erect. Witnessing this, Sumire whispered inwardly, "This is my fault..."