To unlock songs, you must complete the events in the following places:

Song	What to complete
Anthema	Harowa, Ofa
Breathe in the Air	Cadonia, Rab
Disabled the Flaw	Capp, Bagania
Elfadicelli	Harowa, Bonolu
Emi's Song	Manarina, Sasube
Mochi Crunch	Moldig, Istar
On voit la mer	Manarina, Taka
Orange Sky	Cadonia, Bibi
Potpourri d'Orange	Moldig, Apia
Space Space Shooter	Capp, Tamommo
Synergy	Ruby, Dempasa
What is Love ?	Ruby, Recon