Perhaps Leiji Matsumoto's most thoughtful, best developed franchise, Galaxy Express 999 ("three-nine") invites the viewer to join the boy Tetsuro Hoshino and the mysterious, beautiful Maetel as they travel through the galaxy on the eponymous train across the vast reaches of space, stopping at many planets en route to this unlike pair's final destination.
The TV series (1978-1981), 113 glorious episodesEdit
In very the first episode, we'll see an intro that would be a late season climax in any other series. Expect violence, death, and emotional trauma. Oh and btw, this is a show for children. I'm not going to spoil it for you, but Tetsuro is rescued by Maetel and given the fantastic gift of an outrageously expensive ticket to board the Galaxy Express. Something is odd about Maetel - why is a beautiful, wealthy, older woman suddenly willing to help this strange earth boy? We're not gonna find out for a looooong time.
In episode two, the GE999 has arrived at its first stop, Mars. Here we'll get to see more emotional trauma - shooting, stealing, a man shooting his lover, another shooting, a couple pointless deaths. This is a childrens show!
In episode three, the GE999 stops at the moon Titan, where we will encounter wage slavery, sacrificial death, kidnapping, shooting, and other assorted violence. Oh yeah, a nice old lady gives Tetsuro his signature hat and cape (and a gun!). Don't forget now, this is a children's show!
To summarize the rest of the story without spoiling it for you, the GE999 is going to stop (or sometimes be forcibly stopped) at many places where bad things are going to happen (war, genocide, racism, shattered dreams, lost love, lifetimes of futility, eternal torments, etc.). But it's not ALL bad, because along the way there will be some wonderful moments (not very many though) and we're going to learn a lot of lessons about love, sacrifice, hard work, patience, kindness, dedication, happiness, contentment, and ultimately the value of a mortal life. Fortunately, the moralizing is never heavy-handed; Tetsuro is usually left to contemplate what he has learned as the 999 chugs its way on towards the next adventure - it's reminiscent of the books Candide and Gulliver's Travels. Ultimately this series is touching, charming, and fascinating. It's dated in style and animation, but this is a series you watch for its content anyways. It's a long ride, but ultimately it's beautiful and worthwhile.
The films and OVA's (1979, '81, '98, 2000, 2004)Edit
These are different from the TV series and tell a slightly different story, set in the same universe. If you've seen other things connected to Matsumoto Leiji, you'll know that it's not uncommon for later additions to a franchise to contradict previous versions. Some of these have no relation to the original series whatsoever.
The first two films tell a compressed, altered form of the story told in the TV series. Because they're in a much shorter format, the films emphasize action and the main plot of the series, and omit the deeper messages and moral content. These films also try to connect the 999 universe to Captain Harlock's saga (which is barely attempted at all in the TV series). Adieu Galaxy Express ('81) is a sequel to the events of the first film. Watch these after completing the TV series unless you want partial spoilers.
The next film from 1998 (Eternal Fantasy) is a completely new story set in the 999 universe with no relation to anything else. If you're not going to read the related manga, you can skip this one.
The Maetel Legend OVA and Space Symphony Maetel (2000) depict the backstory of Maetel, while at the same time linking the 999 universe to those of Harlock, Space Battleship Yamato, AND Queen Millenia.
And finally, the two OVAs from 2004 (Letter from an Abandoned Planet) are an attempt to tie the 999 of Maetel and Tetsuro into the 'Galaxy Railways' universe, while at the same time linking the two seasons of that series. Most noteworthy because they feature Maetel and Tetsuro drawn in the 'new' Matsumoto style that you'll see in Galaxy Railways or Interstella 5555.