I commented on her evolution a little bit in this post, but I'll ramble a bit more here.
Initially, Maya was meant to be the tomboy character. When I designed her, I thought her voice would be something like Mitsuki Saiga, a woman who's a lot more known for her male voices than female ones. With this in mind, her character was very tough with very few feminine traits. She was a track team star, the kind that lots of girls would have a crush on. She has a lot of male and female fans and a strong sense of justice, even having a signature "justice punch." But for being such a popular girl, she was terribly hard to actually put into a romantic situation. I wanted to show some of her vulnerability, but it didn't really turn out because her type of character was so unrealistic. The school idol type is so fake, and tearing her down and showing her weakness just seemed terribly cliche. Plus, as the tomboy, she didn't come across as a believable older sister.
And so her character and eventually her design took a pretty serious change. Instead of being the school idol and crush, she became a lot less of the "girl prince" and more of "one girl army." A tough girl, but not unrealistic and distant. She's still a track star, but not the perfect kind that always wins no matter what. Instead, I wanted her to struggle and to work hard for her victories, and even fail a little bit. Then her weaknesses would be more human and less cliched. Plus, it makes her a much warmer big sister who is closer to her siblings rather than just being the super cool guardian who they look up to. I think the change in character is a nice one because it makes her a lot more human and much more identifiable.