The idol competition never lets up, but neither does PROTOSTAR's belief that they belong on stage. The soundtrack doesn't just accompany the story, it IS the story, with every performance hitting harder because you've watched these characters earn the right to sing it. This is the show for people who remember why they fell in love with idol anime in the first place: not for the drama, but for the moment when a group of underdogs finally nails a harmony and the camera pulls back to show they've got a crowd.

PROTOSTAR has made their CD debut and, after taking the Rookie Men's Idol Fes, has been enjoying a smooth and successful run as idols. That changes when Lin and Maoto, representatives of their agency, tell the three members they will face LEGIT and JAXX/JAXX in a release battle over their new songs. Both rival groups belong to the same agency, sMiLea Production. The contest sets off a series of challenges for all the idols as PROTOSTAR works to shine in a competitive industry. This second season of UniteUp! is a music series built around idol life and rivalry.