It’s 1940, and the population of Japan is divided over its entry into World War II. Satoko, the wife of a fabric merchant, is devoted to her husband but is beginning to suspect he’s up to something. Soon she allows herself to be drawn into a game in which she enigmatically conceals her intentions.

The once-proud Japanese Ninja disappeared after the war when GHQ disbanded their organization.However, in reality ninjas still exist secretly and it is said that there are 200 thousand of them.And some elite ninjas are secretly operating behind the scenes in national-level struggles.On the other hand, grassroots ninjas often cannot find jobs, and one of them, Yun Yin Jiu Lang, also lives a life similar to that of the NEET generation.However, there is finally a major "endurance" around Ninomaru!

Kei Kuroda, a 28-year-old high school dropout and gambling addict, has a past stained by suspicions of match-fixing and deliberately throwing a fight. To make ends meet, he works at a brothel while spending his days gambling and boxing as hobbies. One day, by a stroke of luck, Kei gets the chance to fight for a world title.