Tyrant

Tyrant was an extremely powerful Danger Beast from long ago. It was known to possess a formidable and incomparable life force. This dragon was always wandering the country in search of prey, devouring any living being that was unfortunate enough to encounter it. It was feared as a personification of calamity, being capable of evolving its body to suit the ever-changing conditions of its environment whether it was the burning sands of the hottest deserts or coldest arctics. In the time of the first emperor, the dragon had developed its stealth capability in order to elude his suppression forces. Even now, having been subjugated and made into a teigu, "Demon Armor: Incursio", the dragon's flesh is said to still be alive and evolving in order to defeat its enemies.

It can be assumed that it was a Ultra class monster.