Fray 

In a world filled with demons, only knights blessed with miracles can fight against their tyranny. During a moment of desperation, Magpie was given a miracle, the one and only flame that can kill demons. But that very flame turns its owner into a demon that thirsts for ashes… “Put in the firewood, if you don’t want to turn into a handful of ashes.” (Source: WEBTOONS) Note: The chapter count includes a prologue.