The story of Haiyore! Nyaruko-san centers around Nyaruko, a formless Lovecraftian-deity of chaos (Nyarlathotep) who can take on the shape of a seemingly ordinary silver-haired girl. Mahiro Yasaka is a normal high school boy who is being chased by a fearsome black alien one night, until Nyaruko saves him. She explains that the creatures from H. P. Lovecraft's works are actually races of aliens, and that she has been sent to Earth by the Space Defense Agency to protect him from being kidnapped by an alien trafficker. Aliens find Mahiro and the Earth strangely attractive, for entertainment, auction or resources. One by one, the Great Old Ones enter Earth illegally. Eventually, Nyaruko and two other Lovecraft-creatures, Cthugha and Hastur, end up being freeloaders at Mahiro's place.[4] Mahiro has become accustomed to his protection detail of Nyaruko, Cthugha, and Hastur making his life fascinating.