Zettai Bouei Leviathan

Leviathan ~The Last Defense~ (絶対防衛レヴィアタン, Zettai Bōei Reviatan, lit. "Absolute Defense Leviathan") is a Japanese mobile game by GREE. The plot features anthropomorphized dragons as characters. It is a freemium game, as the base game is free of charge but game add-ons can be downloaded for various prices. The game was announced in October 2012 and users who preregistered got a rare card.

An anime television series based on the game and produced by Gonzo began airing in Japan on April 6, 2013. The anime has been licensed for home video and digital distribution by Sentai Filmworks.

Plot
Zettai Bōei Leviathan is set on a planet called Aquafall, a fantasy world filled with water, lush greenery, dragons, and fairies.

When a shower of meteorites suddenly bring forth evil creatures that threaten the planet, the fairy Syrup assembles the Aquafall Defence Force. She recruits three girls of the dragon clans to be members of the task force. The story follows Syrup and the dragon girls named Leviathan, Bahamut, and Jormungandr as they work together to battle enemies.

Official

 * Official anime website

Other Sources

 * Wikipedia
 * Anime News Network