read a manga where the mc has split personality disorder or something a while back. He's a...

read a manga where the mc has split personality disorder or something a while back. He's a very timid person who was forced into a war and in order to cope with all the killing and horrible things he's done, his other personality handles it. His parents forced him into the war so he wants to take revenge on them and he hates his brother as well, though I think that his family actually loved him very much and tried to prevent him from going to war, but he was forced to go anyway because there was a stupid bet about whether or not he would break.