Right now I am reading everything that I can by Haruki Murakami. He is the author of "Dance, Dance, Dance", one of the books that Hanako was reading in her story. I've read his first 8 novels, and they all have involve similar themes to KS, especially Hanako's route.
I also read one of his short story collections beofre KS came out, called "After the Quake". Mainly I was looking for the short story "Super Frog Saves Tokyo", and this was due to heavy reference of it in one episode of Mawaru Penguindrum (an anime with some KS themes).
If you decide to check him out, I'd suggest strating with "A Wild Sheep Chase" -- it is a prequel of sorts to "Dance" and it will let you know right away if Murakami is an author you would like or not.
Hanako>Shizune>Lilly>Emi>Rin {100% complete} "痘痕も靨" (If there is love, then smallpox scars are as pretty as dimples) ~ Japanese proverb
You could try wandering son, it's a manga focusing on two teens who each want to be the opposite sex. It gave me similar vibes to KS, due to the whole theme of being an outsider. It doesn't have quite as much focus on romance as KS, but is definatly a moving story.
