Ultraman Mortao has an unknown past and was born with severe flaws. The cracks in his exterior and his lack of primordial energy make him weaker than other warriors.
Having wandered the universe since childhood, Mortao became skilled at escaping danger, but he still could not avoid the countless perils of space. Just as he was about to die, he was rescued by Tregear, who had only recently fused with Gridom. Mortao saw Tregear as an idol and benefactor, and resolutely decided to follow in his footsteps. Along the way, he met Zero, who had run away because he was in low spirits. After traveling together for decades, they parted ways. Zero tore off half his scarf and gave it to Mortao as a keepsake, promising they would meet again when they were grown.
After wandering the universe for thousands of years, Mortao, an illiterate Ultraman who could only speak in sign language, belatedly realized that he had never learned the other boy’s name. To make matters worse, an energy wave from the M78 Nebula knocked him down onto Earth. His energy deficiency had cost him the ability to transform, so he took the alias Akatsuki Mikazuki and happened to meet Yuma, a member of the EGIS security team. After learning about Taiga, he began exploring this unfamiliar planet...
