She's super-hot, true. But Madoka was basically a proto-tsundere, and Hikaru doesn't act too differently from a lot of moeblobs now. As much as I loved KOR when I watched it (and still do) it had some bad habits.
On the other hand, Madoka almost never got mad for no reason, and she never beat Kyosuke up, either. Although arguably a good beating might have helped things along.
In conclusion: the best episode of KOR is the one where she first subs in for her cousin's band and at the end they play "Salvia no hana no you ni" (I had to look it up, it took forever) and the singer tosses the red ribbon to Modoka and Kyosuke, and then Yusaku breakdances during the sax solo. Runner-up: the Graduate episode.