Daughter is pregnant, mother helps solve son-in-law's sexual desire

Because her daughter was pregnant, Rei's mother-in-law came to take care of the couple. Because Kenichi was forbidden from having sex by his wife, even masturbation was forbidden, causing Rei to have extreme difficulty controlling his desires. Knowing this, Rei immediately went to Kenichi, proactively wanting to help him relieve his sexual desires.

At first it was just to help him pump his cock, but Rei herself also had a desire for sexual satisfaction that had not been known for a long time. And then, the two of them crossed the moral line, going down a path of no return...