I've always wanted to play "Sweet Dream" by korean singer Jang Nara ^-^
Also a few songs by Nami Tamaki as well as "Reila" by jrock band Gazette. I'm not sure if there is a piano version to Reila but that would be awesome because I love that song. <3
Also "Blue Graduation" by Gazette would be good too :3

-Keira :P