Lol, what are you talking about? Did you even read the story?
Trying to get him into a better school was wrong? Trying to get him to stop fighting was wrong?
His friends were the wrong ones
His friend was looking for trouble, and he was trying to start fights. Then the main character got blamed for trying to stay out of it. If anything, this story is a lesson that your "friends" will try to make you fail and/or stop you from trying to better yourself.
I think you're the one who has to look at all the aspects. Yes, you're right, the girl should never have tried to "change" him, but theres a bigger picture. His friend was looking for trouble and instigating fights while he (main character) was trying to learn at school. If you want to place blame, it's that he shouldve started studying for his own future (instead of simply for the girl). And if you want to talk about loyalty, then his friends shouldve understood and supported him. Who is going to care about a middle school fights that'll only going to bring about more fighting? Not employers, that's who. ESPECIALLY in Japan where education is everything. I think your comment shows your own ignorance. Apart of loyalty is wanting to see you and your friends win together and it goes both ways. If the main character was expected to stop fighting and support his instigator friend (only one instigated, the other was actually being bullied for no reason), then the friend should also be expected to put aside their pride and selfishness so that he could succeed.
I mean, you see this type of stuff happen all the time especially in gangs. A friend will risk his life and future for his friends. Sure, its never always that simple (no one's story ever is) but at the end of the day, the shit is toxic.
My cousins always tell me, “Don’t let a girl change who you are” and I can totally see what they mean now. You can give a girl everything they want but once they try to control you, it just goes downhill and that’s basically what she tried to do to him. If a girl forces you to choose her over your friends, that’s not love because she’s not letting you be your own person. I can’t say bros over hoes because not all girls are like this, some are actually very nice and understanding. Just make sure you don’t act differently towards your friends who were there for you in your brightest & darkest times and make sure you find a girl who actually supports you for who you are.