Frillsaur is an infamous monster in Dragon Quest VIII that becomes available upon completing the main game. Being a gold rank monster, it is impressively powerful right out of the gate, and boasts some of the highest HP in the game at the peak of it's power.
|Attribute||Starting Stats||Maximum Stats|
|Bonus turn contribution||1.0|
The untrodden groves, day only.
As the Frou=Frou is stated to be Rhapthorne's favorite monster and that Frillsaur is only available in the post-game, it's possible that the dragon is a "pet" that ran away after the death of it's master.