A young couple, Takashi and Machiko, arrive in the bar Quindecim without any recollection of how they got there. The bartender tells them they cannot leave until they first finish playing a game, one in which their lives will be at stake.

A black-haired woman awakens in an unfamiliar place, unable to remember even her own name. She is taken by a girl named Nona to Quindecim, where she is told that she will be an assistant, and is instructed as to the purpose of the bar's existence.

College student Shigeru Miura wakes up in Quindecim, and falls in love at first sight with the woman at the bar. Unable to remember even her own name, the woman asks him to play a game with her, after being assured that it will jog her memory.

Two more people--a young boy and an older man--arrive at Quindecim, but this time, Decim senses something out of place. Before Decim can explain the game to the pair, the older man reveals that he remembers having seen Decim and the bar before!