Undefeated Bahamut chronicle

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.