So much going on in this chapter, it's even more confusing than usual... So we learn that Mitsuki is not good at studying, or at least worse at it than even Aya. Aya is self-conscious as usual, and then the twins and even her mom confuse Mitsuki for a guy, as well. Haven't they already met her? If not, it's still strange, since Mitsuki does not even present herself as particularly masculine here, apart from wearing a shirt (which isn't all that gender-specific, anyway, I think?). Also, we have a undercurrent of Mitsuki getting lost in thought every time the graduation exam is brought up, and by Aya's reaction, I assume it has something to do with her decision of whether to move the States or not. Lots to untangle...
Why is it here? Putting aside all the genre-tag business which may or not turn out the way you think it will, this story is here because it’s a fun story with cute characters, unusual and evocative art, and sweet interactions among the cast.
Not every story is designed to meet your individual emotional needs. It’s possible to just read a story for what’s actually on the page and not obsess about what other people say about it.
What Blastaar said.