Kitaooji Karen

Can't be honest with her feelings.
Went to college with the protagonist.

Back in college, she used to be in the same club as the protagonist. They frequently ran into each other but never grew particularly close. Karen is very prideful and hates being told what she is supposed to do. However, that's just her way of compensating for her lack of self-confidence. Deep down, she's really a very kind and warm person.