If you loved Space Pirate Captain Harlock: Mystery Of The Arcadia, try Galaxy Express 999: The Movie
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

Space Pirate Captain Harlock: Mystery Of The Arcadia
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Galaxy Express 999: The Movie
What they share
Both films are directed by Rintaro, and they sit in Adventure / Animation / Science Fiction territory. If that's the register that drew you to Space Pirate Captain Harlock: Mystery Of The Arcadia, the second film will land in a comparable space — through a different lens.
What Galaxy Express 999: The Movie is
A runaway teen and a ghost-mom doppelgänger ride a bullet-shaped rail through the galaxy. After his planet is strip-mined for parts, Tetsuro boards the Galaxy Express 999 to trade his flesh for a weapon. Maetel tags along, looking exactly like the woman he lost. The train’s next stop: immortality.