I think the story would be that Nagahisa will be the one who would be infatuated with Kimiko then Yuu will do everything to get his heart. I saw some pictures of both of them togethet without Kimiko with them so my theory is that both of them will en up together. This is yaoi world you know. But if Kimiko and Nagahisa will be the one taking the pair then that would also be great. Just my opinion.
Really?? Where did you saw that picture? Can you give me it's link? Yes you're right . This is yaoi world. But it's just that I like Kimiko-sama and I want her to tease Nagahisa-san. Hehe (≧∀≦)
https://mijuxi.wordpress.com/2015/11/08/aikawa-ka-no-konton-taru-mirai/ I remember reading a eng fantranslation a few years back and can't really find it anymore.
Now that girly face guy (friend of Towa and Shinonome) and Kousaka's younger step brother gotta pair up. And both eldest siblings of Aikawa family ( Nagahisa-san ) and Shirahane family (Kimiko-sama) gotta get together.