Slasher Maidens, Vol. 1

Around the world, a phenomenon is observed where those whose mental stress reaches a peak transform into monsters called "Kaijin" and succumb to murderous impulses. Such supernatural events were completely unrelated to proud pervert Asuma Sudo, but after he transfers to an all-girls school while chasing the girl of his dreams, he discovers that the school was actually a front for an anti-Kaijin special agency!