Taka, a shiftless young man, sets off on a quest to find his brother Mune. Teaming up with a quirky new friend and an edgy, mysterious young girl along the way, Taka finds himself taking on a pack of vicious monster cats determined to execute unscrupulous pet shop owners.

Osamu Kogure is a young man who's out of prison and lives in poverty in an abandoned house, working odd jobs to survive. One day, his abusive prison senpai Inui arrives to boss him around. Inui makes Osamu reveal the location of his old girlfriend Koyuki, who he kidnaps, beats and rapes. When a robbery that Inui has planned goes wrong, Osamu's left arm is cut off. Koyuki takes him to a yakuza-affiliated doctor who treats him with an experimental medicine that regenerates his arm back as a monstrous beast hand that makes him lose control. Osamu and Koyuki try to start a new life together, but their past won't leave them alone.