Its about a kid who dreams to be a hero (not sure with this one), his master is a red dragon, there is also a trap black dragon, well the kid kid killed the demonlord by pretending to be a pizza delivery boy, thats how he infiltrated the castle, then there is the adopter daugther of the demonlord who seeks revenge, also one of the generals is a pervert who likes to take pictures. It was a full color manga
Not entirely sure, but uh... Check out 4 Cut Hero I guess? I read that a long while back, so idk really. Some parts sound like it fits.