Styil Magnus
A member of God's Right Seat, this wizened old man in a green robe first crosses paths with Tōma during his time in France. Despite his small, somewhat unsettling appearance, he's a serious threat—best known for his devastating "Execution of Light" spell, which lets him manipulate the hierarchy of basically everything around him. The spell also produces a flour-based guillotine as a side effect, which he uses as a weapon.
He's got knowledge about Tōma's Imagine Breaker that he never fully reveals, and fans often note that he's one of the few characters to figure out Tōma has lost his memories—something that comes up during their fight. The exact details of what he knows remain unclear, adding to his mysterious presence in the series.
Content compiled by AnimeList.moe from publicly available sources.