This explains how Laine and Chorus came to attend the middle school of Planet Academy.
Key of Time
Mechanic Princess Chorus
Electric Wave Princess Chorus
Maiden of the School Planet
Valkyrie Ghost
Meemu Night Flight
First Super Karaoke Competition
Nekomimi Hakkouda Mountain
Strongest Super Girl Akidora
Twelve Dark Moons
The Four Lost Princesses
Valkyrie Flying in the Skies