Guys, I just reread chapter 68 and noticed something, the girl who kissed Fuutaro is
-Not Miku, because Miku is too shy and lack self confidence to do such reckless thing.
-Not Nino, because Nino floods of self confidence and would never fidget out of nervousness and close her eyes in hesitancy like the girl did before kissing him.
-Possibly Itsuki, because she's reckless enough to do such thing but not confident enough to do it with a straight face.
-Possibly Yotsuba, the same reasons as Itsuki +she was the one who kissed him in the cheek a few chapters ago
As fo Ichika, I honestly have no idea about her, since she's good at acting, and her personality isn't as consistent as the other 4