Ogawa is tanned and has bleached blonde hair, her original colour being black. This style of appearance is called 'Gyaru' in Japan.
During middle school Ogawa still had short hair but it wasn't bleach yet, it was held up at the front by one hair band. She was also not tanned at this stage too, her appearance was much more rule conforming.
Ogawa, along with Mifune got jealous of Tomo for spending too much time around Misaki-senpai, they both confronted Tomo but she intimidated them too much. After telling the girls that she'd help them get closer to Misaki-senpai they become somewhat friends. Tomo later tries to get them to confront Carol Olston but they couldn't do it, Carol was too weird for them.
In Omake 1 Ogawa and Mifune both notice how much more Tomo looks like a girl when she's around Jun and blushing.