(from ebookjapan): The Edo Era.

A group of ninjas, the "Blood Wheel Society," headed by a mysterious creature, Majinsai, begins its activities to conquer Japan. The plan was to return the peaceful world to a war-torn one by manipulating altered humans called "incarnated ninjas".

However, one after another, people appeared who defeated the incarnated ninja of the Blood Wheel Society. ---- His name is "Arashi".

This is the form attained by Hayate, a young ninja formerly of the Blood Wheel Society. In fact, the "Keshin Ninpo", which creates incarnated ninja, was a ninjutsu created by Hayate's father, Arashi Oniju...!