Kyaaaaa!
Manbagi-chan, best love rival!
Unfortunatly nothing is mutual yet, but I'm rooting for her! Bet she will confess first! It will be totz cute!
And I agree, the characters are amazingly well integrated with the story. And their is a decent amount of character development for each of them.
At this point, I believe it is safe to say Manbagi is not only a love rival, but also currently a MC (so many chapters dedicated to her). I hope she stays with us till the end.