Blood

Fifteen years ago, a virus was spread throughout the world. Later known as the "Ki" virus, it quickly infected an estimated 33% of the world's population. People who succumb to this virus are gifted extraordinary and otherworldly powers no human can posses-but once in contact with this virus for too long, infected persons crave blood. A hunger none can stop once it begins.

These affected were later known as, "Ki Sehnen", or KS for short.

In such a short amount of time, a third of the world had already succumbed to it. Afraid of the unknown, for it had no cure and limited information at the time, world leaders agreed to confine and execute any sighted Ki Sehnen.

Fifteen years later, seventeen year old Chisa runs away in search of her older sister who had disappeared five years after the Ki Virus was officially recognized by the public. Infected with the virus, everybody says that her sister was most likely killed.

However, no matter what, Chisa knows she's alive.

Which leads her face to face with a bar known as "Clover", the only clue her sister had left behind before going missing.