Luna

It was about a boy with healing powers and he died in his last life and begged the goddess he served to never be reborned the goddess sent him back and gave him a new life with a gift, self healing ability. He sees a little bit hurt in the woods and he remembers that in last life by healing him he was found out by the church and taken to the palace to serve the emperor and then he isolated him from his father and friend and many bad things happend. So he doesn't heal him by his powers he uses some plant I think. The little boy was actually the future empror and he keeps coming back with his magical cube that makes him look like a child. When he find out that the little boy is the empror he stabs himself in the heart just to get away and never see him. Also the empror isn't human he looks like one but isn't and in this world the other non humans basically all obey the strongest which is the empror. In the end they had a child in shape of an egg in the side stories.