so the monster's part is green as well.

That's good to know, until now most of the monsters posted here are white.
For a green one, I tried Pacman:
Image loading...

Edited from an image I found on Google. So partial credits go to this link, which I can't verify because I block that site via my hosts file.

Besides the corners this picture fits all the clues provided in the initial post and comments about green/white monster part.