Apocalypse Bringer Mynoghra, Vol. 4 (manga): World Conquest Begins with the Civilization of Ruin — Fehu Kazuno

The abnormality Atou discovered while defending Dragontan could spell Mynoghra's very doom, for this is no ordinary enemy-It's a character from an RPG! Against their overwhelming other-genre might, Atou leads Mynoghra's forces to battle, but the enemy then seizes an opening to invade the Accursed Lands! With their home under siege, it's time for Mynoghra's newest hero unit, Isla, to take to the battlefield!