Haiyore! Nyaruko-san

Haiyoru! Nyaruani: OVAS
Animated Flash shorts based on the light novel series "Haiyore! Nyaruko-san." In these shorts, Nyaruko, an anthropomorphized female version of Nyarlathotep from the Cthulhu Mythos, is constantly being told off by Mahiro, a normal human boy, for all the crazy or stupid things she does.

In one of the shorts, Nyarlko is drawing a cover design for a body pillow. It turns out that the pillow's subject is a half-dressed Mahiro in what appears to be a hot and heavy scene with Nyarlko. Naturally, Mahiro proceeds to stab Nyarlko in the hand with a fork and threatens to kill her if she releases the pillow design.

Other shorts revolve around various gags and occasionally feature Cthuko, an anthropomorphized female version of Cthugha, who's madly in love with Nyaruko.

Haiyoru! Nyaruani: Remember My Mr. Lovecraft (TV Series)
The story centers around Nyaruko, a formless Cthulhu deity who can take on the shape of anyone it wishes, but particularly the shape of a seemingly ordinary silver-haired girl. Mahiro Yasaka is a normal high school student who is chased by aliens one night, until "Nyaruko" saves him.

First Season: Haiyore! Nyaruko-san
"I'm Nyarlathotep, the creeping chaos always smiling beside you." But you can call her Nyaruko for short. One by one, the Great Ones from the Cthulhu mythos are coming to earth to target Nyaruko and her human friend Mahiro. He's utterly clueless about the true nature of his cosmic conflict and just wants to live in peace.

Second Season: Haiyore! Nyaruko-san W
Nyaruko still wants Mahiro, as does Hasuta. Kūko wants Nyaruko, but believes both Nyaruko's and Mahiro's "first time" belongs to her. Yoriko (the mom) puts up with all of it and cheerfully runs the house where they all live. Mahiro just wants some sanity. He doesn't want to be the love toy of a Nyarlathotepan, Cthughan, or a shots-like Hasturan. He may or may not hold out.