Bui is basically the quiet guy of Team Toguro—and probably the least evil of the bunch, though that's not saying much. He's almost always locked inside his armor, which is pretty much his whole aesthetic. It's only when he fights Hiei that viewers actually see what he looks like underneath: a middle-aged dude with short light blue hair and a scar running down his forehead. When he does talk, which is rare, his voice is genuinely unsettling.
The Dark Tournament was really just a means to an end for Bui. His actual goal was to get another shot at Younger Toguro. He and Karasu had crossed paths with the Toguro Brothers before, and both had lost pretty badly. Rather than disappear, they both ended up joining forces with them on the understanding that they'd eventually get their rematch. For Bui, the tournament served as training to make that happen.
Content compiled by AnimeList.moe from publicly available sources.
