Trigun: Badlands Rumble (2010)

Blurb:
The first new Trigun animation in over ten years featuring all the classic Trigun characters you know and love, plus new villains and heroes!

In town surrounded by quicksand, an outlaw from Vash the Stampede’s past has resurfaced after twenty years. His name is Gasback – and he’s looking to cause a little trouble. It seems Gasback has a serious beef with the town’s mayor, who’s paying dozens of bounty hunters to protect his turf. One of those hired guns is a beautiful woman with a vendetta against Gasback. Will she get a shot at revenge? Maybe, if she can get through Gasback’s bodyguard, Wolfwood. And what’s Vash got to do with this mess? Nothing much – except for the fact that he personally set off the entire chain of events two decades ago!

Source: www.anisearch.com/anime/5359