Kim Nam-joon, 18 years old, class president of Yeo-ju's class, top of the school
He is good at studying, but pretends to be bad at it and helps the female protagonist with her studies. He is an all-rounder with both science and humanities skills.
He is kind to everyone, but he is especially affectionate to the female protagonist, and he struggles with everything every day.
Lady, I am the most difficult problem for you to solve.