You sound dumb as fu**. Have you not read the story at all? Lacks character development? Mf, the book aint even finished yet. There's literally been a drastic character development in Ho-in already.
Also, not every single character needs a character development. This is merely just focusing on the romance between these two boys, and chunwoo learning what he deserves and letting go of his first love who has his own personal issues to work out. Like wtf do you except? Neither of them experience any traumatic experiences during the novel to create such a drastic change in their development like you want it to. Sit yo a** down guy.