MAX 300
Finish the final song in heavy mode with an "AA" rank to unlock the MAX 300 extra stage. Complete the extra stage (MAX 300 in heavy mode, at fast speed, and reverse arrows) to unlock MAX 300 in arcade mode. Alternately, clear 100 songs in heavy mode.

Play as Candy
Complete the MAX 300 extra stage with at least an "AA" rank to unlock the Candy extra stage. Complete this extra stage to unlock Candy.

So In love song
Clear 20 stages in arcade mode to unlock the So In love song.

Kind Lady song
Clear 40 stages in arcade mode to unlock the Kind Lady song.

True (Trance Sunrise Mix) song
Complete the Firefly (Be For U), Dive (More deep and deeper style- Be For U), or True (Radio edit - Kosaka Riyu) songs. Once two of those songs are completed, the True (Trance Sunrise Mix) song will be unlocked.