Rai-Dei is a samurai obsessed with understanding death itself—he believes the only real knowledge comes from staring it in the face. His weapon of choice is a sword with a built-in gun firing from the hilt, and he can swing it hard enough to generate sonic blasts.
In the anime, he's frustrated with Vash for refusing to fight seriously, constantly pushing him to actually kill instead of holding back. Rai-Dei wants what he calls "a real battle," not whatever half-hearted clash Vash keeps offering.
The manga version gives him motorized roller skates that let him move at ridiculous speeds—a detail that shows up nowhere else and somehow works.
Before joining the Gung-ho-Guns, Rai-Dei is the main character of "Trigun: Rising," the seventh chapter of Trigun Multiple Bullets. Set before his villain days, the story shows him protecting a small town from bandits and training a young girl in his fighting technique, Jigengari Ittouryu. He starts off cold and apathetic, killing without hesitation, but gradually opens up to the townspeople. Then tragedy strikes. Whatever happens breaks something in him—he abandons his softer side and goes back to being a pure assassin, driven by an obsessive need to cut flesh with his blade.
Content compiled by AnimeList.moe from publicly available sources.