Saikyou no Ousama, Nidome no Jinsei wa Nani o Suru?

Both feared and respected, King Grey is reborn on the magical continent of Dicathen as Arthur Leywin after a mysterious death. He retains his former wisdom, even though he begins his second life as a baby. Over the years, he begins to master magic and to forge his own path, attempting to correct the mistakes of his past life.