Kaguya doesn't remember who she is or why she has a huge scar on her back. Six months ago, she was found injured and unconscious in a field of bamboo.
Beni doesn't care whether she lives or dies until one day a hero appears before her very eyes. And this hero, who swears his undying loyalty to her turns out to be none other than...a ninja from the past?!
A boy, who always gets bullied is told by his dad that the day he turns sixteen he is going to get someone that will always be with him. The boy, Kazu-kun, believes it will be a fiancee, since his dad got a wife (his mom) and his grandma a husband (his grandpa) on their sixteen birthday, but oh surprise, it is a boy and he is a ninja.
Sanada Beni is 13 years old now and she is part of a ninja family. She is finally a Red ninja after 13 years of age. She takes an oath of loyalty to fulfill all her missions as family's "red ninja" descendant. But the problem is she is still a ninja in training. Four years ago she accidentally met a boy named Kiyoshi Makoto.
The young ninja Kagetora has been given a great honor - to serve a renowned family of skilled martial artists. But on arrival, he's handed a challenging assignment: teach the heir to the dynasty, the charming but clumsy Yuki, the deft moves of self-defense and combat.
Soon after entering high school, Mifuyu is chosen to lead the bodyguards who protect the cheerleaders.