The Sun's Song
You guys 've got to watch this.
Its an Anime drama with romance that has a twist. The story line is about two opposite worlds. The girl can only go out at night because she has some kind of illness that if she's gotten into the sun's rays, (I've researched about the illness, its called XP or Xedorama Pigmentosum, a rare genetic defect in ultraviolet radiation-induced DNA repair mechanisms) she'll die. And the boy is a typical high-school student who loves surfing under the sun.
Kaoru(girl) could not attend school and forced to live a life very far from normal. She sleeps thru the day then goes out at night going to a park in front of a train station singing her songs with her guitar. Then go back home at 4:00 am before the sun goes up, and at home, in her room window, she watches this boy waiting for his friends with surfboards on their hands. She does that everynight until one day, or one night, an isolated incedent changes her life.
The two eventually met each other without Kouji(boy) knowing Kaoru's condition. They fell in love almost instantly. Then one day, Kouji have found out about Kaoru's XP. The love story goes on but you have got to watch the ending.
Watch it here. You have to register before you can watch. Its easy.