Eri and Kiyoshi have been married for three years. Although the couple's relationship is good, the number of times they have sex is decreasing. Eri felt that she was unsatisfactory, but she couldn't ask Kiyoshi, who was indifferent, and she secretly comforted herself with masturbation. One day, she is seen masturbating by her brother-in-law Takeshi who often comes to her play. She affirms Eri, who desperately tries to deceive her, saying, "It's nothing to be embarrassed about." Even though she thinks it's wrong, Eri, who has lost to her curiosity and Takeshi's pushyness, gradually reveals her desires that she has hidden until now.