I'm an Ultraman Account Thief, and from the Start I Make the Four Mysterious Ultras Cry

A tokusatsu veteran who knows the Ultraman series inside and out unexpectedly transmigrates to the beginning of Ultraman Gaia. To survive in a world overrun by monsters, he relies on his knowledge of the plot and decisively joins XIG, Earth's defense force. He becomes an apparently unremarkable communications officer, stationed on the front lines of the coming “Destruction Bringer.”

He believes that “power is the only truth.” He's no saint. When facing an enemy, whether a monster or an alien, if it poses a threat, he'll choose “physical exorcism” without hesitation, leaving no loose ends. Calm and decisive, he also has a bit of a trollish streak. His arrival leaves everyone shocked and bewildered, while he enjoys turning the plot upside down like a powerful account thief.