偶像Fes之后一个月，346 Production灰姑娘计划的偶像们一步一步地拓展着活动而成长着。就在一帆风顺之时，出现了暗中接近制作人的诡异人影……！难道说是制作人的跟踪狂吗！？偶像们开始在工作空闲时轮番护卫制作人……！之后，从海外的346 Production关联公司而来，担任偶像事业部门统括重任的女性·美城常务打出了新的方针……！？

Miku and Riina are concerned with improving as a unit to get ready for “Cinderella’s Ball,” despite their usual clashes over the direction of the unit. Meanwhile, Riina becomes friends with a rock idol she admires, Natsuki Kimura, whom Executive Director Mishiro has invited to join a new rock-idol unit.

Connecting with Natsuki, who is devoted to rock, makes Riina remember how much she loves it too. Riina is torn over what she wants to do. Miku picks up on the fact that Riina isn’t her usual self and worries about her partner, but decides to wait until she is ready to talk...

The fall fest held by 346 Production has begun at last. The Cinderella Project idols are each determined in their own way and fired up as they face the concert. Per Producer's decision, New Generations is sitting the concert out, but Mio and Uzuki are on hand as staff to support the others, while Rin performs with Karen and Nao to make their concert debut as Triad Primus.

Meanwhile, Anastasia performs solo for the first time on stage and all the other Cinderella Project idols shine more than ever. On the other hand, it's the first time for the Project Krone idols to be on stage. Their nervousness reaches its peak right as they're about to go on...

Uzuki has lost sight of herself and lost her smile, but Mio and Rin still believe in her, so they wait for Uzuki to come around. In response to her friends' faith, Uzuki visits 346 Pro, but she still has no good answer to the indecision that's inside her. Mio and Rin decide to watch over Uzuki, who remains in doubt even as she takes a lesson at the office. Afterwards, the other members on the scene share their various feelings as colleagues, friends, and idols.

The encounter makes Uzuki think about what she's currently missing. And then it's Christmas Eve. Producer picks Uzuki up and they head over to the concert venue, but stop off at a certain place along the way...