Hajime, the husband, wanted to have a child with his wife Chihaya, but it was discovered that Chihaya was unable to conceive. Not wanting to be disliked by Hajime, Chihaya asks her mother, Reika, to be a surrogate mother. Though confused, Reika agrees to her daughter Chihaya's desperate plea and begins having sex with Hajime to try and conceive! It was supposed to be just sex to make a baby, but Hajime gets really into it...