There Are Only Night Herons in the Dungeon

"Young adventurer, do you want to conquer a giant dragon as big as a mountain, or a small slime?" "But aren't the giant dragon and the slime both disguised as Night Heron?" ———— Gauss was reincarnated into a night heron in the dungeon and acquired the skill [Perfect Mimicry] that can perfectly impersonate all things. The first person he played was the demon king who was turned into Silly Gugu, and gained the ability to resurrect the dead as members of the Night Heron. In order to fly out of the dungeon, the souls of all the monsters must be gathered together, and the night heron must be used to disguise everything. As a betrayed and fallen adventurer fell in front of him, the three-way game with the native monsters and the adventurer officially began. ———— But Night Heron is not the only one who longs for freedom. The ant with one soul and thousands of bodies, the moth infected by the dream mirror, the slime who inherited the tiger with his body... In order to break through the siege, the monster lords are also fighting today. "Well then, please invite the next genius lord!" But soon Gauss was surprised to discover: "What do you mean there are only night herons left in this dungeon?" Elements: non-human protagonist + lord struggle + loving warrior (?)