After moving into a new home, the Kominato newlyweds become friendly with the wealthy couple next door. Yotsuha’s husband, Yuzuru, has developed erectile dysfunction and their marriage has become sexless. When neighbor Atsushi suggests swapping partners, Yuzuru discovers a cuckolding fetish. The experienced couple trains innocent Yotsuha to crave other men’s cocks, drawing her ever deeper into immoral pleasure...