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 is found lost in the mountains. As Rikka is concerned that someone is pursuing Miya, she also asks the head the of Isurugi Ninja Clan for permission to avenger her father's death. Soon Rikka faces danger with the attack of the Negoro group...