Usami Kei is a salaryman who has risen in status due to his engagement with Mei, the wealthy daughter of his company's president. Shortly after she breaks off the engagement, a power failure leaves him stuck in the elevator of his apartment building. Trapped with him are three others living on the same floor - Airu, a trilingual interpreter; Ojiro, a model photographer; and Masato, a psychiatrist. While waiting, their conversation hits upon their love lives and the question of whether there is truly only one fated partner for everyone. As a result, they decide to try "shuffling" their relationships with each other.