The era when Samurai and Ninja existed in Japan. Rikka Isurugi was born and raised in a Ninja clan secluded from society. She soon meets Miya, a girl with a mysterious power, who got lost in the mountains. Despite Rikka being concerned that someone is pursuing Miya, she asks Hyoue Isurugi, the head of Isurugi clan, to avenger her father. Soon after, Rikka faces danger with the attack of the Negoro group but….