In a certain place, an honest old man was living happily with his beloved grandmother and his dog Hal. However, their next-door neighbors, the family of Grandpa Toraji, were a bizarre and perverted family who abducted and murdered people one after another. One day, the old tinker kills Hal and burns him to ashes. Saddened and with Hal's ashes in his hands, Honest Grandpa turns into a demon of vengeance and begins to strike back at the family.

A serial killer comes to a magical girl who is good at divination. She hides in a closet and overcomes the murderer, who sings the nursery rhyme "Momotaro" as he commits his murder, and decides to exterminate him. Accompanied by Kokkuri-san, Merry-san, and Okiku-san, the magical girl sets out to the accidental property where the murderer is hiding.