Love Me Tear is hosting the annual Aikatsu Song Battle with Karen captain of the White team and Mirai captain of the Red team. Members of Pure Palette, Honey Cat and Reflect Moon divide between the two teams and perform songs for the audience. However back stage there's a mystery to solve, when Coco suddenly disappears from the Aikatsu Mobile the idols decide to investigate.

The next round of the Diamond Friends Cup sees Reflect Moon go up against Love Me Tear. But despite Sakuya's divination they'll be victorious, Kakuya is still worried she'll never be able to match her sister's skill as an idol. But it's not only Kakuya that's worried, Mirai notices Karen is having her own doubts.