Ultraman Episode 18: "Brother from Another Planet"

When a toxic fog falls over Tokyo and starts affecting the people, the SSSP goes to investigate. There, Arashi and Ide spot Alien Zarab in disguise. At first they fear that he is hostile, but the alien claims to be the friend of humanity and offers to remove the fog as proof of his good intentions, which he does.

However, at the time of Zarab's good deed, Hayata was investigating a missing space shuttle that suddenly appeared back in Earth's stratosphere. When Zarab removed the toxic fog from Tokyo, it was sent into space along with the space shuttle. While Zarab had gained Earth's favor, the SSSP had Hayata keep a close eye on him.

When Zarab took his leave from Earth to return to his ship, Hayata followed him. Hayata discovered that Zarab's ship was actually the missing space shuttle and that he had enslaved its crew. Before Hayata could return to Earth, Zarab revealed that he had been aware of Hayata's presence all along since they left Earth. The alien also knew that Hayata was the human host of Ultraman. After revealing his true intentions Zarab imprisoned Hayata, then returned to Earth disguised as Ultraman and briefly began to destroy the city of Tokyo, planing to use Ultraman as the means to cause the humans to fight among themselves.

Zarab then appeared at a council meeting and insisted that the SSSP should attack Ultraman if he returns. This caused much argument among the council members, as they still had faith in Ultraman. Later that night, Zarab disguised himself again as Imit-Ultraman and returned to his rampage. However, Hoshino found where Zarab had hidden Hayata and freed him, allowing him to become Ultraman and clear the Ultra Warrior's reputation. Ultraman managed to shed Zarab of his disguise when the impostor tried to escape. Zarab fought hard against Ultraman but was eventually killed, thus ending his invasion.