When you achieve 100 completion in Dice Master mode this bonus feature will become available.

When you complete the following tasks in Dice Master mode the corresponding song will become available.

Unlock Dead End (Groove Radar Special):
Complete the mission diagonally bottom right of the final mission.

Unlock Kimono Princess:
Complete the mission diagonally top left of the final mission.

Unlock Pluto White Wall:
Complete the mission diagonally bottom left of the final mission.

Unlock Roppongi Evolved:
Complete the final mission in Dice Master mode (Center platform with pictured dance pad).