User blog comment:BalrogLune/Ultra transformation?/@comment-6532857-20141227173303

The one thing the series have in common is that the host and the ultra are one. Off course, they're not the same person, but they're still one. The best analogy I can draw is the Christian concept of the Trinity: Three Persons, One God, although there are some fundamental differences. (Namely that the three persons share individual beings but one nature, because there can only be one omnipotent nature, but it's complicated, and, as any Catholic would put it, a mystery."

Seven, Leo, Mebius and 80, I believe, are their host. The host is just an ultra in human form. So they just grow into their true form. Ultraman, Ace, Jack, Taro, Nexus, Dyna, Tiga, Gaia, Max, Seven X, Zero, and Ginga all use actual humans as hosts. They live in the human, but when transformed, come out and the human is inside them instead. But you should always remember the conversation Mefilas and Man had:

"What are you, Ultraman, an alien, or a human?"

"I am both"

Which brings up another Christian concept, that of the two natures of Christ. You see, the old man Eiji was a convert to Catholicism, so in his works I try to draw parallels. I think it helps one understand them better.