Kizumonogatari Part 1: Tekketsu

Koyomi Araragi discovers the severely wounded body of the vampire later known as Shinobu Oshino, and consequently becomes her vampiric servant tasked with repossessing her severed body parts from 3 powerful monster hunters so she can recover. Unfortunately, for him, as a complete novice to combat and his own body's new abilities, he's hopelessly outclassed.