In Korea, there's a popular tv program where a psychiatrist talks with parents and their children and give advice. One episode had a child who stutters and her advice was good, like, it's the parents who should slow down with longer pauses, don't rush your stuttering child to respond quickly and so on. No Korean celebrity seems to have stutter, unless some of them are masking it so well. Not much media representation either. I can only think of one Korean movie and one Korean drama. The Handmaiden has a stutterer character but his screen time is short. Hell is Other People has two characters with stutter and they are bad people, but almost everyone in the show is bad.