Can't believe Narita busted his balls for nothing.
Going to take a guess that his work will still be worth it. I can't see the work put in by the author in the previous couple of chapters setting the scene being thrown out.
Mitsuki seems like she wants to go, and go with Aya so they could make a late entrance (let's assume what Aya said is not 100% true due to the previous chapter).
Also the Prom might be where we get a little side development between Narita and Mao, possibly? Maybe?