Class 3-E finds a treasure chest deep in a cave, but it turned out to be empty when it is opened. To make matters worse, everyone switches bodies with someone else. With everyone trying to adapt to each other's new bodies, some are faced against Caterpillar Kunudons. Nagisa finds Karma, who have switch bodies, in a hidden part of the cave. It has another treasure chest which contains a Swap Orb, reverting everyone back to normal. However, a Caterpillar Kunudon has switched bodies with Koro-sensei.