Thinking about her mother-in-law who seems lonely because her father is absent, the brother's decision was to have adultery with her mother-in-law.
Kogiku Tsukishima, who married a man with whom she had a child several years ago. Her two sons-in-law treated Kogiku like her real mother, and her home was filled with a warm atmosphere. Meanwhile, it was decided that her husband would be posted overseas, and she told her sons, "When Kogiku is in trouble, I will help her." Kogiku indulges in masturbation alone from her loneliness that her husband is gone. Her sons saw Kogiku's obscene appearance and felt that they had to help her mother-in-law.
