Kanna, a former secretary to the company president, married a man who was a manager due to the age difference. Although she is her mother-in-law, her mother-in-law cares for her son who is confined to her home even though he is an adult and takes care of her son. She was her stepmother who gave her son a massage one day to encourage him. However, as she was massaging her, her mother-in-law was perplexed by the unexpectedly large and firm bulge that swelled up.