Kuina and Rokuro really got on my nerves while reading, I recall. Just very one-note and obnoxious. Ikari is shit too because iirc he gets a whole "no, don't leave!" arc where the whole class tries to keep him around or something when he by and far has the least screen-time/interactions. I've read 170+ chapters yet so little sticks in my memory beyond bits and pieces, like the way mob characters are drawn, or the hilariously fast relationship drama between Shiki and the young blond Momotaro.