Wracked with guilt over the suicide of her bullied sister, young karate student Megumi accompanies four older friends on a trip into the woods: smart girl Aya, her druggie boyfriend Také, full-figured model Maki, and nerdy Naoi. Things start to go badly when Maki finds a parasitical worm inside a fish - and wolfs it down, in the hope that it will keep her skinny. Soon after, they are attacked by a crowd of poop-covered undead who emerge from an outhouse toilet. The group seeks refuge in the home of the strange Dr. Tanaka, who conducts experiments on the zombies and the parasites ... and who has another fate in mind for the five strangers. Can Megumi's karate help them escape, or will she have to rely on the liberating power of flatulence to defeat her demented captor?