A curse binds two families, requiring one person from each to share the same fate for precisely one year every century. Over 12 trials, the pair must alternate between sustaining injuries inflicted upon the other.
Kagura Izumi's life had been unremarkable since his parents' fatal accident when he was seven. However, at age 17, he encounters Ichijyou Chihaya, a mysterious transfer student, starting the two on an interwoven fate. Every 13th day of the month for the next year, they will face a series of 12 misfortunes, unmatched by any previous pair to survive the curse.
