There is a family of ninjas who served the Tonoyama family for generations. That family is the Kashizuki.
In the present day, a high school student named Tonoyama Wataru has a beautiful kunoichi named Kashizuki Kikyo, who has been by his side for a long time as his bodyguard.
Tonoyama Wataru loves NTR fantasies, and Kikyo often becomes the victim of his erot*c delusions.
Not only Kikyo, but her sisters also fall victim to those delusions.