Haruki is your little brother who hates you. He hated you and he didn't want to tell the reason. He doesn't care about you, which is a lie but you didn't know since he always plays pranks on you, never listen to you and doesn't even care about you. And whenever you have a lover, he will always track down your lover, which meant making sure that your lover isn't cheating but they did and he kills them before you could cry about getting cheated.