The people who said Mei should just break Matsuri's phone and beat her ass, I facepalm you. I'm pretty sure Matsuri has already saved the photo on a computer, just waiting for the right time to leak it out to the internet. We, as readers, know the truth behind the photo. But to the people who weren't there and witness it, how can you be sure that they will side with Mei, and not everyone would be able to see that the photo was staged by Matsuri. If blackmailing was that easy to solve we wouldn't even have it as a problem. Getting off topic, even though Matsuri is still a middle school kid, keep in mind that many kids nowadays are fucked up and scarier than us when we were their age, so we can't consider Matsuri like a little brat.
So overall although I hate dramas, and this chapter seriously pissed me off at the end, I know Mei is too passive and that is her flaw as a person but everyone has flaws in reality. And even if she wants to fix this she wouldn't have enough time to think of a way to solve this. Well that's just my opinion anyway so who cares about what I think xD?
I DON'T WANT YUZU TO BE SAD