Hiroyuki, a newlywed, started living with his wife, Yumi's parents, but was turned away by Yumi because of an exchange with a male colleague who was seen a few days ago. Hiroyuki tries to make up and talks through the shower door... but when he opens the door, his mother-in-law, Mari, is there! She apologizes in a hurry, but what jumped into Hiroyuki's eyes was Mari's plump and obscene boobs. She couldn't even imagine, the gentle mother-in-law's too erotic big breasts. Hiroyuki had opened the forbidden door...
