Aikatsu! x PriPara THE MOVIE -Deai no Kiseki-

Akari Oozora and Laala Manaka. Two idols shining in their own worlds suddenly find themselves on the same stage!
A magical encounter between two worlds that was never supposed to intersect: Aikatsu and PriPara!
The idols of Starlight Academy and Parajuku were enjoying a dream collaboration at the joint live festival, but before they knew it the outside world was in big trouble..!?
The perfect stage packed with excitement and glitter! Everyone's friends, everyone's idols — their idol activities begin right here!

(Source: Official Website, translated)