The students have relocated to a nearby island, where they have no shortage of food, and can get whatever they want through Mizuho's power. Suddenly, unexplained fires begin breaking out, and the hunt is on to find out who or what is causing them.

While traveling the wilderness, Mizuho asks Yamabiko how he became a dog. Yamabiko then relates how, 5000 years ago, he wandered different worlds all alone, until meeting a girl to whom he gradually opened his heart. But their happiness was short-lived.