It's Paintball Gundam!
Salvaged post-war by the good guys, this particular Zaku was used for combat practise. No, that big red splat on its shoulder isn't some poor hapless soul catapulted against it during the war!
This is a typical Master Grade kit, with lots of parts, polycaps for great articulation and posing, and with the added bonus of some nice decals for the markings, including the paintball splat (which you can put anywhere you like, of course). Requires an extra bit of work, with some screws to be put into place and a tiny bit of gluing for the three little bits of extra armor on the helmet, which are optional.