The episode opens with some Japanese hikers climbing Mount Fuji. They soon discover a wide path not marked on their map, but they decide to travel on it anyway, and they are attacked by the King Cobra. The show cuts to H.E.A.T. on a french plane to Japan, where they plan to investigate the "Fuji Monster". They find the trail, but it is closed off. They travel into the woods, and find many destroyed buildings. They discover many samples on their hike, such as strange slime and fur. The slime however, is shown to have no organic properties. Just as they discover this, they are attacked by a large monster. They are almost killed, but they are rescued by Zilla Junior. The kaiju begin to fight, but it bests Junior with Judo moves, and proves to be unaffected by his Atomic Ray. The fire from the ray burns off the fur and mask, revealing to all that it is a robot. It quickly restrains Zilla Junior and begins to electrocute him. Mendel Craven tries to disrupt the robot's control signal with N.I.G.E.L., but they are quickly found and arrested by the Japanese military. They are taken to Robo-Yeti's control room, where it is operated by a Dr. Ifukube. She reveals that she is attacking the young Zilla because it had eaten twenty Japanese people, causing Niko Tatopoulos to reason to her that Zilla Junior had not been anywhere near Japan for some time. Nick and Elsie Chapman back up this claim by showing her the slime specimens, and informing her that Junior does not secrete slime, and it must therefore be another Mutation. Nick is then proven correct when King Cobra attacks the facility. Monique Dupre takes a command radio from the wreckage, and beckons Robo-Yeti over, but the Cobra quickly defeats it. H.E.A.T. and Ifukube are then forced to work together, and the Robo-Yeti is repaired. Robo-Yeti goes to Tokyo where it aids Zilla Junior in the battle against King Cobra. Meanwhile, Elsie and Randy Hernandez search for, and discover the Cobra's den, where they find all of its victims in stasis. they are rescued, and the Cobra is defeated.
"What would Gojira be doing in Japan?"
— A Japanese woman on a plane dismisses her little son's 'imaginative' claim
"There once was a robot from HEAT, Whom no one could ever defeat! He takes quite a licking, and just keeps on ticking, which really is quite some feat!"
At one point in this episode, a Japanese child in an airplane sees Godzilla out the window and tells his mother that he sees Gojira. His mother replies "Silly child, what would Gojira be doing in Japan?," an inside joke referencing the character's Japanese origins.