A global pandemic is ravaging mankind and world leaders have failed to stop it… and in this anime, a virus that turns people into monsters is ravaging mankind and world leaders have failed to stop it. A samurai and a ninja from the edo period are transported to the present day and join a team of researchers trying to stop the virus.
Shinichi Sakurai enters college and discovers his high school underclassmen named Uzaki is attending the same school. After observing Sakurai for a full year, Uzaki decides he’s too much of a loner and is determined to pull him out of his shell.
Facing extinction at the hands (claws?) of the Gadoll, mankind has found safety inside the mobile fortress called “Deca-Dence”. A young girl named Natsume is locked into career of maintaining the ship, but her true desire is to be a solider fighting the Gadoll.