After receiving a vision of a mysterious girl held captive by a terrible monster, Shiren and Koppa set out for Serpentcoil Island - a distant island rumored to be the lost stronghold of treasure-hunting pirates. Determined to save the girl and find the treasure, the two face danger... only to be defeated, like all others who tried before. Undeterred, Shiren and Koppa vow to challenge the monster again to save the mysterious girl.

To defy the many dangers that await them, Shiren and Koppa must traverse complex dungeons filled with hostile monsters, hidden traps, and useful items. All of Shiren's equipment and experience will be lost if she collapses during the exploration, so be careful not to rush in unprepared! Save the mysterious girl and uncover the mystery that shrouds Serpentcoil Island!