Mob is very busy preparing for the cultural fair that's coming up in two weeks. Meanwhile, Serizawa is trying to start over, and is thinking about going to night school. That is when a self-proclaimed yokai hunter arrives.

After Psycho Helmet's appearance, tree roots start emerging all around the city. Sensing danger, Mob goes with Reigen and Ritsu to destroy the Divine Tree, but eventually, they are overwhelmed by the members of the Psycho Helmet.