None. MC is a pushover, overthinker, near severe delusion of grandeur, self obsessed in a way, day dreamer who cannot focus, slow witted and being a middle schooler, an idiot with under developed brain.
Ah Arima was so worried he had a rival. But the only rivalry here is Yukihara and Miyahara's love for the Warring States! Pretty strange part of history to like though...
Mr. Ootsuki is simply looking to be a good teacher by reading more about the subject he's teaching. I'm sure he's a good teacher, although it seems he's not a good joker.
Miyahara's such a teaser for talking to Arima about love like that. This cutie is the best!