Idol Sister.

Ayaka, Maki, and Maina make up Platinum Kiss⁠—a popular idol group. They partake in usual idol activities like photoshoots, meet-and-greets, and live performances. Just before they are expected on stage for another live performance, the group is feeling very anxious and unwilling to perform. The reason is that they haven't seen their manager, Ayaka's brother, for a while now. What could he be up to?