A thousand years ago, Enka, the god of destruction, died with the word that its 'child' would destroy the world. In order to prevent this, the Great Japanese Empire Paranormal Phenomena Bureau of Measures begins 'Operation Cozy Family' (code name: 'code-Olympus'). The family is composed of Midarezaki Ōka, an official of the Bureau, and Midarezaki Kyōka, a self proclaimed goddess, as parents; the children are the candidates, human and otherwise, who are potentially the prophesied 'Child of Enka'. The goal of the operation is to discern which child the prophecy applies to, as well as to teach him or her about the love of family in hopes of convincing him or her to not destroy the world. The story focuses on the mishaps and adventures that the impromptu family experiences together.