Reviews

There's a reason this manga isn't labelled yuri anywhere. Although it wants you to believe otherwise, there's no love triangle in the proper sense within the threesome either, despite constant references to the Summer Triangle asterism. After dragging you through five volumes of drama, pretty much nothing is resolved. Instead of wrapping up a mess of a love dodecahedron, the reader is supposed to imagine how things might end up like in the future, which is a cop-out no matter how you look at it. I picked 'mixed feelings' instead of 'not recommended' because the manga isn't bad in itself. The characters are interesting, and feel human and well-developed. The story is actually fairly decent other than the hasty ending, if you're into romantic dramas. The art is great (although shocked expressions are overused), and little recurring themes like astronomy symbolism (which is blatant) and food themed items (which is less obvious) are fun to track. Some readers will certainly enjoy simply watching this complicated web of friendship develop with trial by fire. But any reader that expects the ending to mean something will end up severely disappointed with this shaggy dog story.

Heavy spoilers follow...

Most egregiously, the very core of the plot, the fact that Mikage is aware of the other girls' feelings to the point that it brings her so much angst and drives the entire story, is left up in the air with an 'I'll tell them one day'.
Let me break down the main triangle to illustrate:
Nadeshiko → Mikage: This is the only love interest in the triangle that the manga actually develops. It's revealed at the very beginning of the manga and by the time it reaches the end, although Nadeshiko is aware that Mikage knows her love for her, Mikage stubbornly continues to keep it a secret from the rest for the sake of maintaining the friendship as she's always wanted, despite all the drama this mindset brought about. It's (very vaguely) implied that they might eventually end up together, with Mikage potentially giving in and accepting the idea 'What's wrong with coming to love someone who loves you?'.
Mikage → Tsukasa: We're supposed to think there's such a love interest because a triangle has three edges. The flags are even set in the first volumes in a way that parallels Nadeshiko's attraction to Mikage, but then it's never mentioned ever again. Throughout the manga (outside flashbacks) Mikage shows no romantic attraction to anyone. She simply appears to be interested in maintaining the threesome at a friendship level even if it means forcing her friends and herself to be straight to the very end.
Tsukasa → Nadeshiko: Mikage correctly surmises that there's hope for Tsukasa to be 'normal' again unlike herself and Nadeshiko. (She gives an example of how Tsukasa was excited to hear Kyousuke's confession... ignoring Nadeshiko's ex-boyfriend with the takoyaki t-shirt.) Thus, Tsukasa is left in the dark the whole time as Mikage pushes her to get a boyfriend. In the omake, it is indeed shown that Tsukasa eventually 'grew up', got over her love for Nadeshiko after being led on to selflessly support Nadeshiko's love for Mikage... and just found a boyfriend in the end. (This was apparently ironed over in the English translation, with the boyfriend mention replaced with a 'sweetheart'.)

And the side characters:
Subaru ⟷ Kyousuke: Subaru never grew out of his sister complex in the manga, although it's implied that he's changing as a person as he comes closer to Kyousuke instead. Similarly, Kyousuke's lingering love for Tsukasa was also left unresolved, although it's clearly shown that he's developing a crush for Subaru instead, so I can say that this pair is at least partially resolved.
Kashiwagi ⟷ Maezono: They appear twice in the manga and get married in the omake. Congrats.

The moral of the story is that friendship wins over love, so you had better change and not repeat Mikage's mistakes.