Reading this on a certain friend's death anniversary feels overwhelming a bit, but this did give me some space for imagination. Even if one has to move on in life, it doesn't go away easily. If not for the supernatural tag, the MC would have just fallen into despair. The sad part is, if one observed carefully, Hikaru being replaced and a 'faker' clinging close to Yoshiki feels like him (MC) unable to live for himself and his friend's death haunting him everywhere, cuz believe it or not, he's still a dead body and the real one is no more (as of now, though it may change, not sure) which makes him choose between reality (a world without Hikaru) and pleasure (losing oneself)
Hikaru ga Shinda Natsu