Sergio Island is home to a small population of Japanese citizens, a group of natives, and a garrison of the J.S.D.F.. When a space probe crashes into the ocean nearby, the alien amoeba Yog, who had been riding onboard the probe, sets his sights on the island. Finding a cuttlefish, he possesses it, and creates a Gezora, which he directs onto the island. Attacking a village on the island, Gezora wreaks havoc until the citizens and JSDF set fire to a field. Gezora clumsily wanders into the flames, and gets horrifically burned, retreating to the ocean where he presumably dies. Yog escapes Gezora's body, and then possesses a Rock Lobster, creating the giant creature Ganimes. Once again directing the creation onto the island, Ganimes destroys more houses in the village, but he is too slow to escape a large explosion created with Dynamite, blowing up Ganimes and releasing Yog yet again. Yog then returns to the Ocean once more, and creates a Kamoebas by possessing a turtle, and then he also creates another Ganimes. The two monsters attack the island yet again until a swarm of bats startles Yog, resulting in his control over Ganimes and Kamoebas dissipating. The two monsters now fight each other until they fall into the island's active volcano, killing both of them and finally destroying Yog.
- In Godzilla: Rulers of Earth #19, a framed diploma reading "Selgio Island" can be seen hanging on the wall in Steven Woods' office.