Sen wa, Boku o Egaku - Vol. 3 Ch. 19 - Mirage

[MangaDex]

 

[Leonhart93]

Aoyamas' eyes are bigger than Chiaki's, which is ridiculous since traditionally the females have bigger eyes in this medium. I guess it's used to show the amount of maturity a character has. It fits here since Chiaki is certainly more mature.
And overblown large eyes would not suit Chiaki as good, since she looks very beautiful without those commonly exaggerated features.