Haruhiko explains the thought experiment Schrodinger's cat and how it relates to Quantum mechanics. Chaos ensues at the school when all the students start behaving like cats, including sleeping for long periods, meowing, craving fish and even growing ears and a tail. The team is asked to find a missing kitten which is tracked to a Phantom hiding in a mansion closed years before when it was overrun by cats. Once inside they realize the Phantom is the house itself possessed by a cat spirit who became lonely and angry when the mansion was closed and students from the school stopped visiting. After Kurumi pleads with the Phantom to return the kitten the Phantom is happy with how Kurumi loves the kitten and returns it, returns the mansion to normal and changes all the students back to normal. Before they leave they decide to clean the mansion and the school decides to turn the mansion into a tea house for the students.