Trigun: Badlands Rumble

Vash the Stampede, a gunfighter with a giant bounty on his head, always wearing his favorite red-colored trench coat, is back. Scary as it may sound, he is actually a very nice guy that values life a lot. Twenty years ago, Vash saves Gasback, who is the world's number 1 wanted criminal. Almost. However, twenty years later he finds himself in a town, where, for some reason, many bounty hunters are gathered. Among them, there is also a young lady, who wants to kill Gasback really badly. Why does Vash try to save Gasback's life?