Tyrant Dragon Rex

The Tyrant Dragon Rex is an ancient dragon that was sealed away by the previous heroes.

Volume 4
The Tyrant Dragon Rex was a monster the previous heroes weren't capable of defeating. Instead, they sealed away the monster inside of a sealing stone.

The sealing stone has been watched over the town's nobility for generations and become the iconic legend of the town.

The abusive corrupt nobleman and slaveowner named Idol Rabier would later break the seal to cause havoc and kill the Shield Hero and the rioting Demi-Humans outside the wall.

Naofumi, noticing the dragon's aggression towards Filo, used that to his advantage to lure the dragon outside of town. Naofumi and the team make it to a field, where the Filolial queen Fitoria confronts the dragon herself, swiftly killing it and taking the Dragon Emperor Core from its possession.

Trivia

 * The monster was described to be approximately 20 meters tall and resembling a dinosaur, specifically the Tyrannosaurs Rex species
 * In Japanese, the individual kanji for the word T. rex literally means "Hegemonic King Dragon" (覇王龍) which is why its name is translated as Tyrant Dragon while it looks exactly like a Dinosaur.
 * The Tyrant Dragon Rex is the result of a non-dragon species possessing one the Dragon Emperor Cores. It seemingly mutated over time, gaining the traits of a dragon and thus giving it the name Tyrant Dragon Rex.