Bye-Bye Jupiter is a mess. No amount of sugar coating or dodging around the fact can avoid that conclusion. The movie had a lot going for it being directed by Koji Hashimoto, who also directed the entertaining The Return of Godzilla (1984), and Sakyo Komatsu, writer of Submersion of Japan (1973) and Virus (1980). That said, despite the two doing great work elsewhere, its difficult to juggle a co-directed project and this film certainly suffers from too many ideas. As a whole, the plot is scattered and aimless, the acting is awful outside of the lead, the music is forgettable and yet tragically the special effects are amazing, placing them as the sole positive mark as Koichi Kawakita really poured his heart into something that ultimately fell short in every other area.
In terms of story, it's the 22nd century and mankind is facing a population problem while it continues to expand to planets outside of Earth, trying to make room for the 18 billion people that populate the solar system. In order to expand further, an operation is put into place to solarize Jupiter and turn it into another sun. This plan is put on hold, though, as evidence of alien life is discovered on Jupiter. To make matters complicated, the solarization idea is also met with controversy from segments of humanity, in particular a fraction group called the Jupiter Church. Led by Peter, the group is peaceful in nature, but is driven increasingly violent by Anita, who is trying to get the attention of the sect's leader. Among those trying to stop the solarization is Maria Basehart, a former lover of Eiji Honda who is leading the Jupiter solarization project. However, priorities are completely shifted when its discovered that a black hole is moving toward the solar system on a collision course with the sun. Eiji figures that the only chance to save the system is to create a nuclear fusion on Jupiter, in an effort to redirect the black hole and change its course.
In a broad sense, the plot has shadows of Gorath (1962) except on a larger, solar system wide level. There is a lot of potential to the concept, but ultimately the movie is marred by too many ideas and a lack of focus. Solarization project, Jupiter Church unrest, alien race on Jupiter, black hole approaching, a dolphin named Jupiter and a battle with a shark... all the while giving no characterization beyond a few brief snippets. There is no pay off to a lot of this either, the alien race on Jupiter, dubbed the "Jupiter Ghost", in particular feels aimless. It would have been great had this angle been focused on and the Jupiter church stuff dumped altogether. That way humanity is faced with a difficult choice: sacrifice the alien race they just discovered in order to save the Earth. It would have been a nice bit of conflict, but the movie ignores the alien race altogether... in fact, the alien race only comes up fleetingly at the end as it appears to send a signal out while the planet is being destroyed.
Sadly, a lot of plot time is spent on the Jupiter Church group, which is located on Earth. They get to act as the movie's antagonists, but have no depth to them at all outside of being a peaceful group. They live an easy life out on the beach, singing songs, playing games and hanging out with the group's mascot, Jupiter: a dolphin. The true villain of the story, Anita, is jealous of the lack of attention being given to her by their leader, and sets to amend this by attacking the solarization project, killing workers there and doing general sabotage before joining in a final assault on the complex. Despite Peter being pretty knowledgeable of his followers, to the point of knowing Eiji and Maria's relationship, he seems oblivious to Anita's actions... and that never changes. The whole Jupiter Church story is really lacking on the character confrontation part, and can mostly be described as painfully long scenes of people playing on the beach giving god awful acting performances (more on that later).
In fact, for all of Komatsu's work, this one easily has the worst characters. I have never read the original novel, and assume its handled better there, but the movie presents paper thin characters that are hard to care about. The Eiji and Maria romance in particular is a train wreck. The pair meet after what appears to be a long span of time and on less than ideal terms with Maria attempting to destroy Eiji's work. The pair seem to ignore this though and run off to make love and then go their separate ways until the climax. That's it. The movie does give us a brief flashback and explains that Maria grew contempt for space travel after her parents died, and that Eiji and her separated... during a sequence that shows them to be kids. So they were childhood sweethearts, hardly say a word and just leap into bed together when they meet up years later, and then spend the movie apart up until the final battle. Sorry, but an overly long sex sequence is not a good recipe for developing a relationship that an audience will care about; furthermore, when they do finally meet in the climax there is really no sense of drama for the audience to see them on opposite sides fighting each other.
As a whole, Eiji is the only character worth dissecting here as well. Hardly anything is learned of the rest of the cast, save a few throwaway lines like "I loved him" and having another character speculate on Anita's motives, because this movie seems to be inept at showing rather than telling the audience what is going on (this is a movie, not a book... someone seemed to have forgotten that along the way). Worth noting that the character himself is an homage to Eiji Tsuburaya and Ishiro Honda, and the movie does have a rather large nod to Ghidorah, the Three-Headed Monster (1964) that is, rather sadly, the highlight of the entire film. However, the character is hollow outside of general characteristics such as him being a genius, warrior (seen in the embarrassing sequences where he fist fights his friend as they are rough housing and joking, or when he kills a shark on Earth) and that he seems only half heatedly into his romance with Maria, to the point that he makes almost no effort to see her during his trip to Earth halfway through the film.
As for the acting, Tomokazu Miura as Eiji Honda and Miyuki Ono as Anita give okay performances. They are both clearly trying, but don't have much material to work with and the effort being put in is largely left to waste because of that. The rest of the cast, though, is almost universally abysmal. There is a lot of English speakers here, and almost none of them classify as an actor as far as I'm concerned. The entire Jupiter Church group in particular is amazingly bad, giving no emotion to their lines and sometimes even having trouble speaking them.
For the music, its composed by Kentaro Haneda who has done some decent work, Virus (1980), and also some forgettable work, G.I. Samurai (1979). Sadly, this score is more of the latter than the former, as its largely forgettable. It's not unenjoyable, but gives definition to the word transparent and does little to heighten the experience like a good soundtrack should. The songs, done by Yumi Matsutoya and Jiro Sugita, fare much better and are actually pretty enjoyable, although Sugita's Bye-Bye Jupiter (or Sayonara Jupiter) has the misfortune of being tied to very cheesy scenes of Peter and the Jupiter dolphin playing together in slow motion.
In regards to the special effects, simply stunning. Kawakita gives a performance high in his work for this picture. There are a few blemishes, such as the Jade 3 which doesn't look convincing and the horrible shark which we will gloss over and just pretend doesn't exist, but otherwise the effects work is jaw dropping even by today's standards. The sheer scope and size of the gigantic crafts is well captured, and the planet work is also done very well. It's one of those few times since the closure of the golden age of Japanese cinema that the effects could have stood up to some of the Hollywood blockbusters of its time. Sadly, the project is so tarnished in every other sense that Kawakita's efforts here are largely forgotten amongst his larger resume of work today.
Bottom line, Bye-Bye Jupiter is a mess to the point where there is no easy fix. Better actors from the supporting cast, a number of plot lines dropped, better characters... at some point it just stacks up so much that one throws up their hands in surrender. It's hard to imagine, but I would much rather watch Jun Fukuda's The War in Space (1977) over this film, as at least the other picture is fun in its pacing while Bye-Bye Jupiter is more of an endurance in trying to put up with everything that goes wrong at nearly every turn.