Thirteen year-old Sanada Beni is part of a ninja family. After years of training, she is finally a Red ninja. She takes an oath of loyalty to fulfill all her missions as her family's "red ninja" descendant. She sets off to the same school attended by Kiyoshi Makoto, a boy she accidentally met four years ago. Now, what will happen as Makoto continues to protect the entrance ceremony - and Beni protects him?