This challenge is that Harry at a young age becomes part of one The Four Satan's Peerage. The Satan that you choose can see Harry becoming a powerful wizard. So they make Harry a devil after seeing Vernon beating him to death or almost to death.
-Harry is the same age as Rais and Akeno.
-Harry can't have harem.
-Harry is not godlike. He learning to be a devil and learning multiple types of magics.