It's autumn and the season of changes: Sawaki is once again seeing microorganisms, Kei decides to renovate the sake brewery Hiyoshi with methods as personal as they are radical, and Hasegawa has disappeared. The last time she was seen, she was getting into her father's car. The little group will have to do without her for the harvest festival, which is just as wacky as the spring festival, especially with Misato and Kawahama's great ideas.