I wonder if their ED song music genre like jrock, ballad, etc is based on their characters and personality. I really like kaoru's ED song..
So
haruka - J-rock
kaoru - J pop
If i were to make guesess for other heroines, the genres would be
Sae - Tecno pop/bubblegum pop
Ai - RnB pop
Rihoko - classical pop
Tsukasa - Ballad
I guess being just a VA's is not enough, they have to sing well too
.My favourite - maya sakamoto