A tiny flower from space called Tigris Flower whose seed had arrived on Earth over a hundred years ago, Right at the end of the second age of aliens, the seed was planted by a local boxer named Kotaro Higashi. At the dusk of the day Oil Drinker appeared on land and Tigris Flower began to emit pollen from it's flower that knocked Kotaro out and would have eaten him if ZAT had not found him. Within minutes, Tigris Flower grew into his adult form of Astromons. One night, the final chouju of Yapool, Oil Drinker appeared and ZAT came to the area to battle with the chouju. Agitated, Tigris Flower formed into his adult form Astromons and battled with Oil Drinker. It didn't take long for the massive plant to eat the choju when Oil Drinker's head got stuck in his massive flower chest. After the battle, Astromons flew away into the night. The next day, Astromons attacked once again. ZAT soon appeared, and attacked once it got too close to its base. During the attack, Kotaro's plane was hit, and sent crashing into the ground. Moved by this man's courage, the Ultra Brothers and the Mother of Ultra granted him a new life. The female hero placed his latest son, Ultraman Taro, into Kotaro. Not a second later, Ultraman Taro attacked Astromons. Taro attacked with many punches and kicks, until Astromons struck back with his acidic mist, allowing his to get multiple hits in. Taro managed to use the Storium Ray, however, the massive plant monster was destroyed for good.