I'm looking for the name of a mecha movie or OVA. It's a short about a squad of UN troops or mercenaries in a desert decommissioning weapons. They're equipped with pink laser and lots of rocket launchers, encounter a walking robot tank that gradually kills off most of them with its own pink laser, and one survives at the end, when he loses his armor and dogtags so it thinks he's a civilian.

There was a short about samurai fighting an oni before it in the same material.

pic unrelated.