1192, the Kamakura period. After being murdered by his brother Minamoto no Yoritomo, Minamoto no Yoshitsune came back from the dead by borrowing the power of youkai. As an herbalist, you accidentally learn the truth of the dark secret and get involved in the revenge plot. Then, the small fox that you saved before suddenly turns out to be a mythical creature! “I grant the one with an innocent soul permission to form a contract with me.” Trapped in the turmoil brought by the Minamoto brothers, an unexpected love story thus unveils…