Lovely song:
Get a 80% Great rating on G-Pop on stage 1. Complete stage 2 with Lounge. The hidden Lovely song will appear on stage 3.

Positive song:
Complete stage 1 with Cute and stage 2 with Magic Girl. The hidden Positive song will appear on stage 3.

Jungle song:
Get a max combo score of 100 on stages 1 and 2. The hidden Jungle song will appear on stage 3.

Prelude song:
Get a score of 85,000 or more under Advanced and a score of 90,000 or more (with a max combo score of 40) under Classic 3.