"Diga" means "light", symbolizing human beings and unknown power.
In 2025, giant monsters suddenly appeared in many places around the world, and cities were destroyed one after another. In response to this catastrophe, the United Nations urgently established the TPC Earth Defense Command and formed the elite combat force "GUTS" with the sole mission of "destroying monsters and protecting mankind."
GUTS ace pilot Makaku Oko's fighter plane crashed during a mission against the monster "Golzan". When he was about to die, he merged with the mysterious light and transformed into the giant "Ultraman Tiga" to fight off the monster. This sudden light giant caused a global shock: TPC executive Gondo Kihachi regarded it as a "potential threat" and secretly promoted the "artificial giant project"; while GUTS commander Megumi Kama discovered that the connection between Dagu and Tiga may be related to the legend of the "Light Watcher" spread in the super ancient times.
As monsters such as "Melba" and "Gakuma" appear one after another, Dagu gradually masters the power of Tiga, but he is also caught in a dilemma - humans' suspicion of him, the power struggle within the TPC, and the dark shadows hidden behind the monsters are all testing the trust of "light and humans". When the ultimate evil god Gatanjie arrives, Dagu must make a choice: fight as a human, or become a "god" that transcends humans?
"Light is never the power of one person." This time, Tiga's light will be lit up by humans and giants.
