The brothers decide to commit adultery with their stepmother Kogiku because they think that their stepmother Kogiku is lonely because their father is away. - A few years ago, Tsukishima Kogiku married a man with a stepchild. - Kogiku's two sons-in-law adore her as if they were her real mother, and the family is enveloped in a slightly warm atmosphere. - Meanwhile, it was decided that her husband would be posted overseas, and she departed, telling her sons, ``When Kogiku is in trouble, help her.'' - Kogiku indulges in masturbation alone because she is lonely without her husband. - Seeing Kogiku's lewd appearance, the sons felt that they had to help their mother-in-law, Kogiku.