After death, most humans face Heaven or Hell, but a few end up at Quindecim, a bar where those who die simultaneously are judged. The mysterious bartender, Decim, acts as the arbiter, challenging patrons to life-threatening games that determine whether their souls will reincarnate or vanish. As the patrons play, their true natures are revealed through games like darts, bowling, and fighting. However, when a black-haired amnesiac arrives at Quindecim, Decim begins to question his impartial judgment, leading him to reconsider his methods and the meaning of life and death.