Ultraman: Daigu Is Gone from the Start

After being injured, Shinjo Tetsuo, a member of the GUTS team in the Ultraman Tiga world, awakened memories from his "past life" and learned that his world was actually a tokusatsu series called Ultraman Tiga. He'd originally planned to lie flat and rely on the main character, only to discover that the original protagonist, Daigo, was already dead. Then, by chance, he inherited the light of the sky from the Gaia world from a mysterious girl in red, transforming into Ultraman Uranos. Recognized by both Alaya, the collective human consciousness of the universe, and Gaia, Earth's consciousness, he took the place of Ultraman Tiga, who was supposed to protect this world, and defeated the monsters that kept appearing as well as the aliens trying to invade Earth. While protecting the planet, Shinjo noticed that more and more girls were gathering around him. Besides his younger sister Mayumi, there were Lucia, an alien girl on the run; the idol Chris Maya; Yuzare, an intelligent life-form from the Ultra-Ancient Civilization; the artificial intelligence Kallen; and others...

Also known as Shinjo: I Have a Whole Lot of Sisters

This novel and its characters are entirely fictional. Any resemblance to real people or events is purely coincidental. Do not imitate.