Japan in the near future -- throngs of evil spirits and monsters run rampant. Though humans and demons once had a pact of non-interference in the other's dealings, a rise in human degeneracy created a rift between the two. Criminals and companies began to utilize demonic powers for their own gain, and the world fell into chaos.

However, those who tread the path of righteousness were not helpless. The government created a special unit of ninjas who oppose the demons with their own bodies. People called them "Taimanin"...

There's an abandoned island in Tokyo Bay called "Tokyo Kingdom". Asagi has tracked the demons' allies to the island, but it was all a trap by the hateful Oboro. Now Asagi, Sakura, and Murasaki have been caught, and are at the sexual mercy of monsters...