Alderamin on the Sky

Ikta is a brilliant, but lazy and unmotivated boy. His childhood friend, a high-ranking daughter of a noble, offers him an easy position at a library if he can help her get the top score on a military exam. But their lives take a sudden turn when the boat carrying them to the exam runs aground, and Ikta rescues a mysterious girl on board. When she turns out to be a princess, and they all find themselves behind enemy lines, Ikta is going to start having to work hard for real...