Steth arrived on Earth prior to Jiya to investigate for the galactic patrol upon arriving was astonished by beautiful thriving world. While investigating it he encountered a monster known as Vamp. After possessing him he became corrupted and decided to take over the earth. In order to keep any other Galactic Patrolman from arriving he created a false report about the earth. After he arrived and reveals his true identity to be his former comrade Steth who took over Vamp's body and caused terror on the Earth using giant alien fleas called Mogans from the Planet Kanoi.This arrangmnet continued until Kyuumonji Yukio while possessed by Jiya shot one of the giant fleas as they swarmed the town for their usuall feeding. After this happened Vamp ordered one of the Morgans to kidnap Yukio's boss Kaede. After Jiya returned to his body he attempted to fight the Morgans and Vamp who had come to fight Jiya. During the fight Steth inside of Vamp's body revealed his true identity and his plan to cause terror on the Earth.
During the fight Vamp was distracted by Kaede as Jiya was being powered up through the use of alcohol. When Vamp started to lose the fight his possessor Steth left his body and attempted to possess Kyuumonji's body only to be killed by Kaede.