I sang a bunch of J-pop songs for my vocal class a couple years ago...lets see what I can remember....
Toki no Hourousha (ok...so it's from FF..but its still in Japanese)
PURACHINA by Maaya Sakamoto
Yubiwa by Maaya Sakamoto
and a bunch of other Maaya Sakamoto/Bonnie Pink things....my voice isn't too far off from theirs so the songs were easy for me to sing.
Actually...when I first sang PURACHINA everyone in my class went mental wanting to see the lyrics and hear it again and ask me all about everything Japanese I could tell them. It was kinda crazy o_O
This year I fully intened to nail Utada Hikaru's Passion for my class.