Police officer Shintaro Jagasaki lives a stable life with a girl he's dated for years. Their future seems all mapped out--marriage, a family, children--but it all feels unbearably dull. With a few screws loose (and his frequent fantasy to open fire on civilians to show for it), Jagasaki's mind is anything but stable.

Then, out of the blue, people suddenly begin to contort into monsters driven by primal urges to commit violence. And as chance has it, Jagasaki also gains a grotesque body-morphing power which transforms his right hand into a fleshy gun. A newly made monster and mentally unstable, Jagasaki becomes an antihero of ambiguous morals and dark impulses.