It was an absolutely secret relationship. She had stolen her son-in-law's heart and body. She knew it was wrong, but she couldn't stop. Tsubaki was having a drink in the evening and listening to her son-in-law's complaints. Perhaps because of the alcohol, the son-in-law embraced Tsubaki. Feeling lonely, Tsubaki gradually accepted him... One night, the son-in-law sneaked into Marika's bedroom. Knowing about the strained relationship between her daughter and son-in-law, Marika ended up accepting her son-in-law... The son-in-law touched Natsuko's body, seeking forbidden pleasure. Natsuko knew it was wrong, but she thought it would help her feel less lonely... In the past, only missionary position was permitted for marital relations. Aya, who had only known that, was shocked by her daughter and son-in-law's sexual practices...