Minamisato Ai is the shy girl that has a crush for both, Tooru in the OVA and Tsuyoshi in TV Serie. So shy she blush almost anytime either one speaks to her! If it wasn't because of a bit of pushing by her friend Miyuki...

She takes part of the OVA and is the main female character in TV Serie (even though there is an episode that does not feature her).

It is difficult to compare her character from the OVA and TV Serie. Given that the TV serie did gave more time to develop her character, at the end, she is a different person than at the beginning. However, she still is the romantic girl in both. #4 on my list.