Undefeated Bahamut Chronicle complete collections contains episodes 1-12.
From the charred pieces of the corrupt Arcadia Empire, a new kingdom arose. To protect itself from future foes, the Kingdom of Atismata established the Royal Knight Academy to train warriors in the art of fighting with Drag-Rides, ancient mechanical dragons.
The Academy has a catch though: it’s strictly a no-male school, and when the former prince of the ruined Empire, Lux, stumbles into the baths, he lands himself in a compromising situation with Lisesharte, the new kingdom’s princess. Understandably upset, and challenges him to a Drag-Ride duel, launching their lives into an explosive chain reaction that will expose the dark secrets of both royal families. Whether Lux is fighting off monsters, corruption, or his female classmates, things are sure to take flight into the unpredictable skies.