Mika lost her husband in an accident and had been living alone with her daughter. After her daughter got married, Mika began living with the couple, and their life together was happy. However, she started overhearing the couple's nightly intimacy, causing her body to gradually grow aroused. She began relieving her desires through masturbation. One night, after drinking together, Mika fell asleep. While she was out, the couple started having sex beside her. Mika woke up but pretended to be asleep. Her son-in-law then noticed her and told her he had seen her masturbating, before seducing her into sex. Though she tried to resist, her body could no longer hold back, and she ended up giving in. From that night on, Mika's heart began to stir once again.