To get this you'll have to beat the 32 core songs on hard. So these ones...
Cat Food
Secret Police
Melancholic
Weekender Girl
Time Machine
DYE
Fire Flower
Summer Idol
ACUTE
Urbandonment
What Do You Mean!?
Stay With Me
Hm? Ah, Yes.
Remote Controller
Ashes to Ashes
World's End Umbrella
Freely Tomorrow
Monochrome Blue Sky
Glasses
Kagamine HachiHachi Flower Fight
World's End Dance Hall
The MMORPG Addict's Anthem
Nostalogic
Nyanyanyanyanyanyanya
Unhappy Refrain
Odds & Ends
Tengaku
God-Tier Tune
Black Rock Shooter
Negaposi Continues
Sadistic.Music Factory
Continuing Dream