Once upon a time, there was a war over the "special gun"... Poncho, a young man who hides his past and lives in a bar, meets a mysterious girl, Sapphire, who has a special gun "Water Revolver". Poncho stands up again to help Sapphire, who says she is being targeted by her army! When the past is revealed and the true power of "Water Revolver" is released, it will trigger a "new war" involving bandits, corrupt armies, and dark organizations!