K - Stray Dog Story

Yatogami Kuroh has lost the only thing remotely close to family he had left—and to make matters worse, he's been charged with a final task by his master that he isn't entirely sure he'll be able to fulfill. Follow this young modern-era samurai as he sets off on a quest to track down the next Colorless King and determine if he's evil or not…and to strike him down where he stands if he is.
(Source: September Scanlations)