Kenichi Sarumata lives all alone in a dilapidated house. One day, he discovers a mysterious scroll hidden within the wall—a secret text passed down through the Sarumata family for generations. It contains the ultimate teachings of *injutsu*—an erotic art form akin to ninjutsu, but centered on the mastery of sexual techniques. When Kenichi chants the incantation, a kunoichi named Kaede appears.