Mei's character development is great to see, she has come a long way.
let's try not to jump to conclusions on Harumi having feelings for Yuzu, Harumi hasn't showed any sign's of any romantic Interest towards Yuzu at all. Harumi is just a good friend to Yuzu that all. She being supported of her best friend Yuzu relationship with Mei.
Saburo uta has been giving a lot of hits that she planing on having Harumi & Matsuri end up together as a couple.