Aya is the brightest Gal out of the trio. Aya attends CRAM school, has the best grades, and is the top student in her class. But she was at one time involved with subsidized dating for money, but Ran talked her out of it and became friends with her. Before she became friends with Ran and Miyu, she was a serious student who didn't do anything but study. She has never done anything for fun before she met Ran and Miyu. Now she's involved with the Gal life, and having fun hanging out in Shibuya.

Spoiler

She has a crush on Rei, but as she's so shy and insecure that she has a rough time approaching him.

(Source: Absolute Anime)