Isuca

Isuca (イスカ, Isuka) is a Japanese action manga series by Osamu Takahashi. It has been serialized in Kadokawa Shoten's seinen manga magazine Young Ace since 2009; the series has been collected in nine tankōbon volumes as of May 2017. An anime adaptation by Arms started to air in January 2015.

Plot
Shinichirō Asano is a practical high-school student who gets a job as a housekeeper in order to pay his rent. When he unintentionally releases a strange creature into the world he learns that his female employer, named Sakuya Shimizu, is the head of the Shimizu clan that hunts these creatures. Shinichirō cooperates with her to hunt down the monsters that are running loose.