A new song is unlocked after clearing a specific song in either easy or normal.

Song	How to unlock
ACUTE	Clear Time Machine.
Ashes to Ashes	Clear What Do You Mean!?
Black Rock Shooter	Clear Odds & Ends.
Continuing Dream	Clear Sadistic.Music Factory.
Dream-Eating Monochrome Baku	Clear Tokyo Teddy Bear.
DYE	Clear Secret Police.
Fire Flower	Clear Melancholic.
Freely Tomorrow	Clear Hm? Ah, Yes.
Glasses	Clear Ashes to Ashes.
Hm? Ah, Yes.	Clear ACUTE.
Kagamine HachiHachi Flower Fight	Clear World's End Umbrella.
Monochrome Blue Sky	Clear Remote Controller.
Negaposi*Continues	Clear Tengaku.
Nostalogic	Clear Glasses.
Nyanyanyanyanyanyanya!	Clear Kagamine HachiHachi Flower Fight.
Odds & Ends	Clear The MMORPG Addicts Anthem.
Remote Controller	Clear Urbandonment.
Rin-chan Now!	Clear Sweet Devil.
Sadistic.Music Factory	Clear all other songs except Continuing Dream and songs tagged as "Extra".
Senbonzakura	Clear Rin-chan Now!
Stay With Me	Clear Summer Idol.
Summer Idol	Clear Weekender Girl.
Sweet Devil	Clear Dream-Eating Monochrome Baku.
Tengaku	Clear Nostalogic.
The MMORPG Addicts Anthem	Clear Monochrome Blue Sky.
Time Machine	Clear Cat Food.
Tokyo Teddy Bear	Clear Tell Your World.
Unhappy Refrain	Clear World's End Dance Hall.
Urbandonment	Clear DYE.
What Do You Mean!?	Clear Fire Flower.
World's End Dance Hall	Clear Freely Tomorrow.
World's End Umbrella	Clear Stay With Me.