Tsukimonogatari

Tsukimonogatari (憑物語) is the tenth Monogatari arc, a Japanese light novel series written by Nisio Isin and illustrated by Vofan. An anime adaptation by Shaft began airing on December 31, 2014, comprised of 4 episodes.

Plot
Koyomi Araragi is studying hard in preparation for his college entrance exams when he begins to notice something very strange: his reflection no longer appears in a mirror, a characteristic of a true vampire. Worried about the state of his body, he enlists the help of the human-like doll Yotsugi Ononoki and her master Yozuru Kagenui, an immortal oddity specialist.

Quickly realizing what is wrong with him, Yozuru gives him two choices: either abstain from using the vampiric abilities he received from Shinobu Oshino, or lose his humanity forever.