Historically, it was known as the War of Magic Crystals. The war involved dozens of kingdoms of various sizes, including the foreign Hollyma Kingdom and its tributaries, the three kingdoms of the Sea Alliance and their allies, the Mermaid Kingdom, the Colossus Kingdom, the Hailuga Kingdom, the Wizard Kingdom, the Elf Kingdom of Sun, and the Silver Moon Kingdom on the Yala Continent.
There was a redistribution of power on the sea. The waters were fully controlled by the Mermaid Kingdom and their allies were being invaded by many enemy forces. With the emergence of aircraft, battle airships, and sky fortresses, the supernatural powers in Maria's World had started to conquer the sky. The era of the sea was slowly transforming into the era of the sky.
"On my mark! Fire the annihilation element main gun on the Alva Sky Fortress!"