Murakami has described Worm as a symbol of inner evil, which is a broad and flexible definition. Worm may represent the wickedness hidden inside the city of Tokyo (the criminal corruption that Katagiri battles every day) or the malice hidden inside the hearts of individual people. He may also represent the internal terrors of the imagination, a notion that Frog discusses often throughout the story. Because Worm apparently cannot be killed and his violent outbursts occur cyclically, Murakami seems to be arguing that human beings’ inner evil is similarly persistent and difficult to defeat. Frog complicates this reading when he says that he doesn’t consider Worm to be “the embodiment of evil.” Worm is not evil himself; rather, he is like a vessel that collects hatred from other sources.