Shuumatsu Nani Shitemasuka? Mou Ichido Dake, Aemasuka?

It's been five years since the battle at Corna di Luce on Sky Island 11 and the situation has gotten worse. 5 years ago, about two days after the battle at Corna di Luce on Sky Island 11, the Elpis Mercantile Federation accidentally lost control and released two beasts, Materno: The Fifth Beast Who Spreads Widely and Croyance: The Eleventh Beast Who Remains Rooted both onto Sky Islands 13 and 39 respectively. The result was catastrophic. In the end, both Sky Islands fell to the Beasts and many lives including those of the Elpis Mercantile Federation were lost.

5 years later, Feodor Jessman, a young 4th Grade Officer whose step-brother was at the head of the Elpis Mercantile Federation attacks, spends his days training on Sky Island 38, hoping to climb up the ranks of the Guardian Wings Military to achieve a mysterious goal. One day, while skipping training to buy some doughnuts, he meets a young Leprechaun girl named "Tiat Siba Ignareo" who mysteriously asks him to forget her after a brief conversation. The next day, Feodor is assigned to be the caretaker of visitors from Sky Island 11. As the group arrives, Feodor is surprised to see Tiat among them, along with Lakhesh Nyx Seniorious, Collon Rin Purgatorio and Pannibal Nox Katena.

Little do the two know, their meeting will change the very fate of the Sky Islands; as Sky Island 38 is set to be attacked by Croyance who is steadily approaching the island in Sky Island 39 even now; and a secret conspiracy lurks in the depths of the Guardian Wings Military.

(Source: SukaSuka Wiki)