Yukinoshita Yukino.
I'm probably just glorifying the show, but I liked how it handled its characters, particularly her. There was no aspect of hers I found far-fetched, forced, or awkward. Essentially, she's an over-achieving girl who's grown cold and reserved towards everyone. Her best aspect might as well be her consistency. She doesn't break down into an archetype or ends up hungering for the main character's justice stick like any regular romcom. She remains at a distance, like something you can't get.