Nagisa and Saito have been together for five years and expect an ordinary date, until he brings her to a hotel suite and produces an engagement ring. After proposing, he reveals one more important request: he wants her to sleep with other men before they marry. Nagisa is reluctant, but she does not want to end the relationship now and eventually gives in to his persuasion. One unknown man after another then appears before the submissive bride-to-be.