Science Ninja Team Gatchaman

The Great Underground Monster War (1x10)

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Suddenly, a whole city has lost power. Ken, in his Cessna, is thinking about an anomaly in the power plant when he gets a message from Nambu that the nuclear power plant has been attacked by a large group of ants. The Science Ninja Team goes to the site in question, but since the missiles would have hardly any effect on the tiny groups, they wash them away by breaking a nearby dam and using the force of the water. Upon analysing an ant they brought back, they learn that it's a finely and precisely manufactured robot.