Being a son of a cat demon and a human isn't all it's cracked up to be. As a half-demon, Niko has a unique ability: he can control his demon transformations. However, while he is participating in a Martial Arts tournament, where the best of the best are competing. During his last fight with the last opponent he would expect, his demonic powers become uncontrollable.
Meanwhile, Chisai Konami is falling asleep in class... again, when a sudden illness causes her to collapse, and change into something new: a synthetic cat demon.
With the help of the mysterious Lord Tora, who helps Chisai control her newfound powers, and allows Niko to uncover a powerful attack, these two begin on a new quest to pay him back. However, when danger arises, will these two half cat-demons be able to bring their "A" game?