I read this manga a few years ago. It was read left to right, and was in English. I remember it being fairly entertaining and I’d love to find it!
All I remember is that there were two nations, one with angel-looking people and the other with demon/dragon-looking people. The main character looked like the prince who had gone missing so he was chosen to act like the prince so the kingdom didn’t freak out or something. Also, I remember there being a gigantic magical pink cat who also had horns.