Daicon Film's Return of Ultraman

Daicon Film's Return of Ultraman is a 1983 Japanese superhero kaiju parody fan film directed by Hideaki Anno. The film is a sequel to two previous Ultraman fan films produced by Anno; in the latter of those two, Ultraman leaves Earth, and this film's title refers to Ultraman's return after the events of the previous film.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.