The story begins in the Kingdom of Hillsland five years after the events of Kyonyuu Fantasy Gaiden. A naked man who has no memories finds himself stranded near a harbor. The man, Mask, while oblivious to his nakedness, speaks to a passing woman and gets promptly arrested. Soldiers take him to Molgrey castle where Mask offends the castellan and is consequently thrown into the Zorro prison. But Zorro island is a base of smuggling activities. For witnessing this unlawful secret, Mask is sent on a suicidal mission to Boobshire. He is ordered to kill the monster who has already killed many bounty hunters that ventured to exterminate it. Can Mask defeat the monster or will he perish like the others?