One year has passed since the events of Inyouchuu Kyou and the battle of the demon hunter agency, the black cat brigade, against the demon Gyuki.
During this time, Sui has continued her training as exorcist and has become indispensable in the agency's operations because of her ability to track purify monsters.
Mikoto, who used to be the main exorcist in the agency, is feeling like her position is being threatened and, despite being good friends with Sui, she can't help to feel jealous of her. It doesn't help that Sui, thanks to her newfound confidence, has become bolder on her advances to Yamato, whom Mikoto is also secretely in love with.
Because of her feelings, Mikoto's powers have weakened and she almost fell victim to a monster because of it.
Her friends decide to help her and following the advice of the Tsukishiro twins, Ouka and Kikuka, they attempt a ritual to restore her powers, but something goes wrong and Mikoto is sent back to the past, at the end of the Sengoku era. It's now up to her friends to go to the past and bring her back before anything happens to her.
Meanwhile, In the past, Mikoto is taken prisoner by a band of Oni that has taken residence in the local castle...