According to Japanese folklore, Burubura ''震々'' is called the spirit of cowardice. They follow people and make them shudder in fear.

Buruburu are born when a person commits a cowardly act, such as leaving the battlefield. They take possession of a person by grabbing him by the collar and touching the back of his neck. This makes the hair stand on end and causes trembling throughout the body.

The words "buruburu" and "zo" are Japanese onomatopoeia for the sound of trembling and chilling fear. The name of this spirit comes from the goosebumps that run through the body because of it.