Human beings have always thought that they are the only intelligent lifeforms around, but they couldn't be more wrong. There are many things that happen in the history of humans that cannot be explained by science nor history within the human world. Feral humans are appearing, they look human but they are a threat to the human species, they have been named " Sha". Normal human beings are totally unable to deal with these Sha, so before Sha are found out by the public, a group of mysterious individuals formed an enforcement department - Song of the Black Night.