Three years ago, Serizawa was troubled with about his psychic powers. One day, he was visited by the boss, Suzuki Toichiro. Serizawa ends up trusting him since he's the first person to understand what he's going through. But Mob then brings up the fact that Serizawa is being used and tells him, "I'll be your friend." Hearing Mob say that, Serizawa... Meanwhile, after defeating Sho, the boss starts gathering up the energy he was sharing with his followers and turns into an energy monster.

Mob, Reigen, Dimple, Serizawa, take a trip up to a secluded hot spring called Ibogami Hot Springs in Zebra Prefecture. Reigen happened to get a request from the matron there to discover the truth behind the strange rumors going around there and save the inn. Ritsu and Teru also join in on this trip but on their way there, Reigen and Serizawa start nodding off on the train and somehow get sucked into an eerie parallel world...