Wake Up, Girls! was an idol unit active from 2014 to 2019 whose leader was none other than Yoshino Aoyama, voice of Hitori "Bocchi" Gotou in Bocchi the Rock. In this performance of the opening theme from Restaurant to Another World, originally a collaboration with Mayn, she's the one singing the very first line, with the light blue ribbon.
Far from the absolute nobody before Bocchi the Rock she's sometimes painted as (also by her own presentation), she had before already led this unit throughout the years, culminating in this final concert in a brimful Saitama Super Arena in front of about 35,000 people (full concert playlist) that wowed her senpais Rie Takahashi and Reina Ueda.
During the unit's active years, she also voiced the character based on herself in various accompanying anime productions.
After the unit disbanded after this concert, the only other member that continued to be significantly active in the idol and/or anime space AFAIK is Minami Tanaka, who e.g. went on to become part of Franchouchou in Zombieland Saga.
All spoilers must be tagged!
Also Wake Up, Girls! had an anime project the same name, which I can recommend if you liked the more realistic depictions of the industry in Oshi no Ko (it does not have a murder mystery, nor a reincarnation or a teen pregnancy plot).
Yes, I watched it (the first season at least) and quite liked it. It's what brought on this post basically. I had decided to watch it when I was looking for my next idol anime after my "gateway drug" Zombieland Saga, and the connection to that via Minami Tanaka, and also that I vaguely remembered Yoshino Aoyama was part of it, were what gave the impulse.
There are also a few Wake Up, Girls! anime movies that I couldn't watch yet, and a continuation series "Shin Sou". The drastically altered character designs in the latter unfortunately felt off-putting to me, after the more realistic style of the first season.