You can unlock the song TokyoEVOLVED by playing through groove circuit mode again. There are also 3 songs in the japanese version that are not in the U.S. version, they are:

DOUBLE TORNARD-evo-X
difficulty
beginner-2
basic-4
difficult-6
expert-8

TRUE LOVE (Clubstar's True Club Mix)-jun feat. Schanita
difficulty
beginner-1
basic-3
difficult-5
expert-6

BOSS SONG(s)

Pluto the First-White Wall
difficulty
beginner-3
basic-7
difficult-9
expert-10