Nyarko-san: Another Crawling Chaos(2012)

Mahiro Yasaka is just an ordinary high school student, until one day he is suddenly attacked by a dangerous monster. Just when everything seems to be lost, he is saved by a strange girl named Nyaruko, who claims to be the shape-shifting deity Nyarlathotep from horror author H. P. Lovecraft's Cthulhu Mythos.