Eri and Kiyoshi have been married for three years. Although their relationship is good, the number of sex they have is decreasing. Eri felt unsatisfied, but could not ask Kiyoshi, who was indifferent, so she secretly consoled herself with masturbation. One day, my brother-in-law Takeshi, who often comes to visit, catches me masturbating. Eri tries her best to mislead Eri, but Tsuyoshi insists on having a relationship with her, saying, ``It's nothing to be ashamed of.'' Even though Eri thought she shouldn't, she succumbed to her curiosity and Takeshi's pushiness, and gradually revealed the desires she had hidden until now...