Though Godzilla takes center stage among Toho kaiju and sci-fi fans alike I also think that the Toho Motion Picture "space operas" were also very good. By this I mean films in which the story centers on invading aliens and/or other adventures in outer space, e.g. The Mysterians(1957) and Battle In Outer Space(1959). My favorite Toho science fiction "space opera" is Gorath(1962) (Yosei Gorasu), released to theaters in 1962 by Toho.
The film's story: a mysterious collapsed star with a mass over 6000 times the Earth's is discovered by the crew of a rocket ship. That rocket ship is captured by the celestial body's immense gravitational pull and consequently destroyed, but not before sending back critical information on the approaching red star, which is subsequently dubbed "Gorath". The information is analyzed and the result isn't good: Gorath is on a collision course with Earth, prompting the world's top scientists to forum in an effort to devise a plan to save the planet from imminent destruction. Their plan is a bold one: construct massive, subterranean thermonuclear rockets at the South Pole, fire them off and use them to "thrust" the Earth out of Gorath's projected course. There are the expected logistical headaches that come with such a colossal undertaking, not to mention the appearance of Magma, a giant, disagreeable walrus that obviously does not like all the commotion going on around him at the South Pole. (no other spoilers).
Observations: a fun film and a great spectacle to watch. The music is superlative, the cast a veritable "Who's who" of Toho actors, and the miniatures are, I think the absolute best I have ever seen in any Toho kaiju/sci-fi film.
Gorath was theatrically released in the United States in 1964, a couple of years after it's release in Japan, by Brenco Pictures. In the Americanized version of the film the sequences with the monster walrus "Magma" are removed. I have seen a copy(or two) of the Columbia release of the movie on VHS in discount video stores, though not recently. The film is available on Region 2 at Yesasia.com(though without English subtitles).
The trailer for Gorath(1962):