Jotaro Aragaki is a 29-year-old widower and father who has devoted his life to gymnastics but is now staring down the barrel of retirement, having performed poorly over recent years as he battles both aging and a persistent shoulder injury. However, he’s loathe to tell this to his daughter, and a chance encounter with a foreigner ninja (and a group of mysterious ‘agents’ hot on said ninja’s tail) are about to change the course of Jotaro’s life.