Why are people even complaining? This is a perfectly normal mindset of a high schooler, especially when she always in second place aiming for first. It's quite normal for humans to compare themselves to one another and strive to become better, and all the more so because it's Japan. No one is perfect and the fact that she's falling apart because not only is she second but the life she desired (to be with Ohga) was taken from her, added that she's misunderstanding Hishiro's smiles because Hishiro's awkwardness, this is a perfectly normal result. If you don't like Kariu's character and her development, well I can't help you there but at least try accepting that there's nothing wrong with her character. Also what Kaizaki saying is right, for every moment you hold on and keep putting effort, that hard workingness that you show, someone will definitely notice (and why Kaizaki got accepted to ReLife). So it's better to keep trying then give up and resort to underlying methods. (By the way, the quote I just said, I got it from the other manga she made, Blue Hearts ;w