Koji is a regular employee who has never been successful. Today, he won a rare big prize at the horse races, and as a reward to himself, he went to a high-class soapland...and to his surprise, his wife's mother appeared there! "M-mother-in-law?!" "Koji-kun?!...Please! Don't tell anyone!" Koji was surprised by his mother-in-law's hidden side, forgetting about his situation of cheating on his wife and having fun... "Hey, why did you come to a place like this...you haven't done it with that girl? If you keep it a secret, I'll give you a great service..." Even though she is his wife's mother, he has been interested in her amazing voluptuous body for a long time. He gives in to temptation and gives in to her orders...and her unprecedented, superb meat bomb technique begins to envelop his entire body!