The story revolves around a 16-year-old boy (15 at the beginning of the story) named Mahiru Shirota who likes simple things and dislikes difficult things. One day, he picks up a stray black cat he finds in the middle of the road and gives it the name Kuro (which literally translates into "black"). From this moment on, a contract between the servamp Sleepy Ash and Mahiru is formed, and Mahiru is pulled into the Servamp war between the seven deadly Servamps and their eighth sibling Tsubaki.
Servamp (Sub) Comments