The city of Shinjuku in the near future. A wave of multiple murders has hit, shocking even for this crime-wracked city. The victims are always drained of their body fluids... and there is always a sole survivor.

Behind the murders stands Ekou. For centuries, he was the Karas, the guardian of the town, but he no longer heeds the will of the city, and is intent on destroying it.

There is only one hope for Shinjuku — Otoha, the one who is to be the new Karas. He must now battle Ekou's forces to save the city and its inhabitants, be they human or youkai.