Miho's been dating her boyfriend for five years, and marriage is still nowhere in sight. One day, she casually picks up an issue of the wedding magazine, "Sexy", and sees that it includes a special commemorative supplement. Interest piqued, she takes it out, and suddenly Hayato, a handsome man she's never seen before, appears! "I'm gonna transform you!" Dragged outside, she finds herself in a fancy clothing store. She enjoys her newfound prettiness; it's as if she's become a different person... However, then the domineering and arroagant Hayato's compulsory nighttime training begins... "But I have a boyfriend... What's going to happen to me...!?"