An alien-spawned, mysterious mist blankets the northern half of Japan, transforming those who inhale it into ravenous, flesh-eating zombies zombies hell-bent on devouring the surviving human population.

Plunged into chaos, Japan is torn in two - the southern half of the country, where the populace remains untouched by the deadly gas, lives behind a heavily-fortified wall, while the northern half is a lawless, zombie-infected wasteland.

Hope arrives in the form of Kika (Yumiko Hara), a beautiful high school girl armed with a chainsaw sword powered by an artificial heart. Recruited by the government, Kika leads a ragtag group of desperados on a secret mission into the zombie-infected wilds to exterminate zombie queen Rikka (Eihi Shiina from Audition and Tokyo Gore Police) and put an end to the plague of the living dead.