The story takes place in July 1590, when Hideyoshi Toyotomi finally united the country by destroying the Hojo clan. Sahei and Koyane of the "Kurohabaki-gumi", a ninja group under Masamune Date, visit Sakasai Fort on the northern edge of Hojo's domain.

The fort is isolated and ninjas known as the “Fuma Party” are still holed up there, unaware of the surrender of their lord Hojo.

The mission given to the two is to urge Fuma to give up in order to save their lives from the remnant hunters...

What do the ninjas on the losers' side fight for, left behind in the northern fortress?
And what is the result of the fateful confrontation between the Kurohabaki and the Fuma?