Ruijerd Superdia

The former leader of the Superd's Warrior group who once served Laplace. He accompanied Rudeus and Eris in their journey.

Laplace betrayed his group by giving them each a devil spear which made them ecstatic from killing, even their own family. After giving his son a fatal wound, his son managed to destroy the devil spear and Ruijerd finally wakes up from the brainwash. He considered committing suicide but decided not to and everyone of that warrior group swore revenged on Laplace.

He finally got his revenge after several years of hiding. He interfered in the battle between Laplace and the three heroes. But even if Laplace was defeated, there was no way to change the things that had already transpired.

After exacting his revenge, he now has a goal of removing the infamy the Superd race has.
(Source: Mushoku Tensei Wiki)