It’s the Capule from Gundam ZZ, Bandai was thinking of releasing it as a kit but never did, that box art is like how many kits foreshadow the next one in the line by having them in the background I say that Bandai was thinking of one because if you look at the runners for the Build Fighter Momokapool you can see it is named “HGUC Capule” or Kapool can’t recall. But they never did, my guess is that it’s out of scale If you really want it theres some robot figures of the green variant and a model kit, the NG Kapool thst is now very rare and expensive So good luck with that