Kageaki Minato
About
A war orphan, he was taken in by an old friend of his father and made part of the Minato family, a bloodline tasked with guarding a terrible curse. As he grew up he made his living as a simple salary man together with his new mother Subaru and younger sister Hikaru, trying to make do in this war torn land.
This all came crashing down however once his sister was stricken by heavy metal poisoning, making every day she managed to stay alive a miracle. Unbeknownst to anyone, this would start a chain of events that would lead to the death of his new mother, the relationship with his sister forever altered, and Kageaki himself being bound by an oath, the Law of Balance. A law that stipulates that for every time he slays with hatred, he must slay an equal amount in love.
(Source: Full Metal Daemon Muramasa Wiki)