The long wait for the third season is over. Netflix released it last 5 March 2020 with ten episodes. And yes, I binge watched again.
The film tells the life story of Chiyoko and how she got the key and lost it. It started when, as a teenager, she met a a painter and revolutionary rebel whom she helped escape from the authorities. It was this stranger who gave her that key. They promised each other that they will meet someday. Chiyoko held on that promise and the only way for her to track down the stranger is to become an actress.