The protagonist is not reborn into the past as an overlord, but reborn into the past as a "nanny" and "guide" to the biggest villain. When he was still very weak, he had to avoid all forces that would be enemies of him in the future, and at the same time, he had to help the future demon king grow from a useless boy to a top powerhouse, and at the same time, he had to secretly plan to change his original tragic ending.
