Sion Sunkland

First Prince of the Kingdom of Sunkland, a country that boasted a proud lineage and power on par with the Tearmoon Empire. He is an all-around genius who displays great talent in everything, and is a good young man who strives for "fairness" and "justice".

In the previous timeline, he was one of the enemies who condemned Mia as "an incompetent ruler", helped the leader of the revolutionary army, and was present at Mia's execution.

(Spoiler from Volume 2 of the LN)
By the way, his evaluation of Mia in the previous timeline was not based on his own direct discussion or turning with Mia, but on her superficial behavior and evaluation of people around her, that is, just from rumors. For this reason, although his behavior toward Mia was "correct" as a result of "her actions", it's actually quite problematic from a bird's eye view.

For that reason, Ludwig, who knew all about Mia, a human being, for better or for worse, rejected to work for Sion because he was "an ideal monarch who never made a mistake" but because of that he probably will never understand how Mia felt... and how much she tried.