The era when Samurai and Ninja existed in Japan. Rikka Isurugi was born and raised in a Ninja clan secluded from society and has met a girl with a mysterious power named Miya, who got lost in the mountains. Contrary to Rikka being concerned that someone is pursuing Miya, she commits to Hyoue Isurugi, the head of Isurugi clan, for the revenge of the father. Soon after, Rikka faces a crisis by the attack of the Negoro group, but..