A Civilization Guardian, Ultraman Max's job was to study developing civilizations and help devise a way for the various species of the universe to co-exist. His later mission was the planet Earth which was facing a crisis brought about by man's folly. However, it was stated that Max's first arrival on said planet dated way back in the distant past.

Max observed Earth and witnessed the bravery of a native youth named Kaito Touma. Rather than leaving him to a cruel fate, Max merged with him and allowed them both to protect the people of Earth. After saving Kaito, Max began to fight monsters from Earth's past and invaders from space that wanted the destruction of either humans to have the planet for themselves, with DASH fighting alongside him.

During his battle against Zetton, Max was being severely beaten by the legendary monster and would have died if not for the appearance of Ultraman Xenon, a fellow member of the Inter Galactic Defense Force. During that battle, Max gained the Max Galaxy, a multi-purpose device that saved Max many times afterward and be used to destroy his old enemy Gilfas.

Months later after stopping numerous monsters and invaders, the Delos People rose up to threaten the surface people of Earth. Max could not interfere because it was against the laws of his home world of the Land of Light to interfere with wars between native civilizations. However, Kaito stopped any such conflict, while also saving Mizuki from a near-death experience, by making Delos change his mind and call off the war, they both agreed that neither side had actually wished for a conflict.

The people of Delos requested Max to stop their now rogue defense system, allowing Max to attack their superweapon Giga Berserke. However, between rising to the surface and flying to battle, Max had little time to fight.