I’m surprised. I thought the girl who traumatized him was going to turn out to be Kotoko’s sister. I’m sure some convoluted explanation will exonerate the new girl. My love of gyarus hasn’t closed my judgment in the least.
It had a niche with gals(That dont even exist nowadays as the typical anime gals) a lot of years ago. And otakus hate it and has a slut and trashy stereotype.
So author just wants to make the girl hateable by average reader.