Chapter 13

Procedure (手続き) is the thirteenth chapter of the Oshi no Ko manga series. It is written by Aka Akasaka and illustrated by Mengo Yokoyari. It was released in Weekly Young Jump on August 13, 2020, and in Mangaplus on May 11, 2022.

Summary
Miyako officially signs Ruby to Strawberry Productions, which also permits her to attend a performing arts school.

Later, Aqua visits Taishi's studio. He assists the director with his editing duties as a method to gain industry experience, given he is not yet old enough for formal part-time jobs. While Aqua works, Taishi talks to him about his and Ruby's first steps into the entertainment world, and Aqua negatively reflects on his acting capabilities and approach towards becoming an actor. Taishi advises him to not give up early and to have more confidence in himself.

Ruby and Aqua start the interview process for Yoto High School, with Ruby applying for the performing arts program and Aqua applying for the general education program. After their interviews, they experience a reunion with Kana Arima, who is currently a student at the school.

Characters

 * Ruby Hoshino
 * Miyako Saitou
 * Aquamarine Hoshino
 * Taishi Gotanda's Mother (debut)
 * Taishi Gotanda
 * Kana Arima