尾姐揭秘时间：新公演初日成员是通过甄选选出来的

https://youtu.be/pP3mXBAQH78
On how the new theater stage shonichi members were selected:
Miu said an audition was held for members and that they were given a week to prepare for it. They did about 2 songs per group, with 16 people each, like how they usually do in the theater.

When Serika went back to the waiting room after the announcement, other members, especially Miu, were so happy for her. They congratulated her and told her, "You deserve to be chosen, Serichan!" It made her really happy. It made her glad that she chose to continue on this path.

Forgot to mention but Miu also said that the 2 songs they did in the audition were songs they usually do in the theater btw.
省流：一周准备时间，两组各16人表演两首剧场曲.大白芹很高兴自己坚持了这条路。