Classroom for Heroes, Vol. 2 (novel)

Retired Hero Blade is enjoying school life to the fullest. Now that he's made one hundred friends, he plans to relax and take in the "normal" life. But that may not be possible, what with the Overlord's daughter declaring Blade her rival, a battle royale breaking out in class, and a monster bird attacking the capital.

Plus, Earnest attempts a fiery diet, and it turns out Blade never learned to swim. Each school day brings a new adventure, and a new chance for Blade to make even more friends!