Unlike Ultra Seven who can change the size of the body spontaneously, Ultraman remains unchanged as a 40-meter-tall giant.
But Ultraman becomes life-sized just one time.
It’s not spontaneously but he is shrunk by Dada in “Human Specimens 5 & 6” (Episode 28).
Dada is called just Dada instead of Alien Dada though he’s an alien set as from Planet Dada.
The three-faced alien is here to collect human specimens for an unknown reason.
Dada has a demanding boss who gives him instructions from his home planet.
His boss called him “Dada No. 271” and tells him to finish collecting the human specimens by “Dada Time 222.”
He shrinks humans found suitable as specimens by an equipment he calls Micronizer, if put in English, which looks like a gun.
He’s so weak in battles and beaten up by Ultraman.
He’s beaten even by Cap. Muramatsu when life-sized.
Dada tries in pain to shrink Ultraman by his Micronizer.
But it ends up shrinking Ultraman just human-sized, and Ultraman giganticizes himself immediately with ease.
The fact Ultraman can giganticize himself makes us feel he may be able to reduce to the human size spontaneously like Ultra Seven.
But this is the only time we see him become human-sized.
This episode makes us feel sorry for poor Dada working under an annoying boss and beaten up to a pulp by Ultraman.