Subterranean Boss Roquat is a hidden boss that is encountered after defeating (Obstinate) Valley Ruling Kalidah Level 15 (600,000 HP). It has 900,000 HP and can only be defeated once within the normal 2 hour time limit. Upon defeating the boss, Young Princess Ozma is rewarded to the player who discovered it.
Immediately after defeating it, the evolved version (Order) Subterranean Boss Roquat will appear.