A big-assed mother in her 40s comes from her parents' home in Morioka, Iwate Prefecture to her son's room in Tokyo. She changes her underwear in the room, as if she were at her parents' house. The son can't help but be drawn to her plump buttocks protruding from her plump breasts... After a long reunion, the skinship between mother and son arouses his sexual desire, and he falls into lust!