I wonder if Mei ever thinks about Arata is interested in Yuzu. The small amount of interaction between Arata and Yuzu clearly shows that Arata likes Yuzu. They are also both extroverts. Any crush that Arata has on Mei when they were kids is irrelevant now that they have grown up. I think that Arata probably considers Mei to be a future close friend, why Yuzu being a future girl friend.
As I wrote earlier, my school did exactly something similar. The school founder built two schools, one is for boys, the other for girls. Eventually for social and economical reasons, they merged. Now because of harsh economic situation, we ended up selling the original girl campus, but we survived. If the two school did not merge, both will go bankcrupt.
This proposed school cultural festival by Mei is a HUGE gamble and she better explains it carefully to the board. As Sayaka said before, the school is a bird cage, preventing any student from knowing the outside world. To be more specific, boys. Since many students are already engaged, most of them probably have never met any boys other than their own family circle (such as relatives) and the fiances. But now we have an opportunity for the students to meet with boys from a boy school, and work together, many (on both sides) may end up falling in love (puppy love, whatever you want to define it). This can potentially ruin many engagements. This will become the nightmare scenario that Sayaka fears. The unknown outside world. What will happen if Miyabi meets a boy from Arata's school and started having a crush? Miyabi has no obligation to tell Sayaka everything. What I am trying to point out is, Mei is playing a dangerous game. Engagements being canceled can mean business alliances being broken for the rich who has been inter-marrying for a couple hundred years. Even if Arata's classmates are all from the rich and the upper social class, wrong alliances can cause serious problems.
I hope the board knows what is going on, and I hope Mei has the answers ready.
The truth is also that if Mei does not do something like this, Aihara academy may not last long. It will be like a leak from a dam when the students see what the outside world is, and one by one their families start to send their kids to co-ed schools. Arata's school will also have the same problem, if not more, because boys surely love co-ed schools. Well, except a few..we don't even know if Arata is straight, bi, or gay at this point, all we know is he and Yuzu gets along very well just from what we see so far. But then again of course he himself may already have been engaged.
Oh, I am surprised that Matsuri seems to have a much better relationship with Sayaka. Although I am not surprised that Sayaka does not want to say anything about the festival regardless of whether Mei told her not to say a word about it, this is exactly the scenario she fears about, but has to go through with it, just as she has promised Miyabi (and Yuzu). My feeling is that she does not know the details, based on Himeko's expression, who seems to know a bit but not everything.
Sabu is too slow. I am sure she signed a contract with Yurihime to know how many volumes she would need to produce. Dragging the story will fulfill the contract, but that is a short sighted business strategy. Move quicker, create better arcs, HaruMatsu, etc. A longer sighted strategy will be not just doing that, but finish the manga good enough to have a new sequel (post marriage, College days) with no restrictions anymore. Namori is still drawing not just one, but two series of which one of them is a side story. IF she can do that, and still doing strong, there is no reason Sabu cannot do the same.