A mother who has been horny after a month of abstinence... her son cuckolds her

Kyoka is ordered to live a <ascetic life> for the month her husband goes on a business trip. "If you hold back, it would be better to have sex when you come home." Believing in her husband's words, Kyoka held back from masturbating and was waiting for that day. However, by chance, his son Kenta hears the story. Kenta observes his mother becoming increasingly frustrated every day. And a month after he was welcomed... Kyoka quickly walks to the entrance to pick up her husband, expecting to finally have sex, but for some reason Kenta is there...