My Best Friend's Mother's Alluring Bare Skin (2006)

Kenji, a university student, invites his classmate Yukihide to spend his summer vacation working part-time in his hometown. Kenji has a girlfriend named Aiko. In his hometown, he also has a girlfriend from high school, Aiko. Coincidentally, they share the same name, but unlike the free-spirited Aiko, Aiko has only ever known Kenji. Upon arriving at Kenji's family home, Yukihide is astonished by the beauty of his mother, Michiko...