Talk about a dumb wimp MC, be aware of yourself damn
No real-life high school dude would accept getting blackmailed by a girl without doing anything, and I really mean no one, even the weak quiet slim type dudes
He easily could have forced her phone out of her hand lol... It would've been a different story if they were younger but they're highschoolers
He literally could have taken the 4 of them in a fight, if they would even fight back, just threatening them with violence should be enough
I find it only fair to beat up, or at least threaten, people who are willing to end your social life by blackmailing you just for a few hundred bucks...