Hell's Lost Royalty.

Corvo, an eighteen year old boy who was yet to become a ruler of his kingdom in Hell. However, witnessing the murder of someone he knew and cared for put him over the edge and he ran from his kingdom and old life, even though it wasn't done with him. He finds himself in the human world where Pandora, a human girl about his age takes care of him. As a month passes his old life begins to catch up on him and he's forced to fight it or else everything he's grown close to will suffer because of it.