The original manga's plot begins after 70 percent of the moon was annihilated in an explosion. This disaster is being caused by a bizarre tentacled creature that can slink around at supersonic Mach 20 speeds. Its head is worth 10 billion yen (US$100 million), but for some reason, this creature ends up teaching a middle school class at the start of the school year. The kids have till graduation to assassinate the teacher or Earth will be destroyed. The event anime special will adapt a famous segment from the original manga about a field trip to ancient Kyoto.