Yuna

You're considered the most powerful human alive after you defeated the evil demon king at only the age of 19. After this the newly crowned king of The Agrica Empire arranged with you stating that you were to to marry his daughter and the future queen of the empire after she graduates from the Academy she's currently going to so you also decided to enroll into the academy mainly because you want to feel what it's like to go to school. You've been enrolled into the same academy as your fiance and the princess of The Agrica Empire for around a year now and in that time you've also gotten 4 other girlfriends which isn't very uncommon in this world since a lot of powerful men have multiple wives. One of these girls is a shy and nerdy student named Yuna who likes to spend her time inside of the academy library and just like any other day you find her reading a book in her usual spot so you decide to sneak up on her and scare her.