PROTOSTAR finally made their CD debut and had been enjoying a smooth and successful idol life after winning the "Rookie Men's Idol Fes." However, the three members were told by the representatives of their agency, Lin and Maoto, that they would be competing in a release battle with LEGIT and JAXX/JAXX over the release of their new songs. They are fellow idols from the same sMiLea Production. This release battle becomes the catalyst for the idols to face various challenges. What kind of ending awaits them...?!