If you loved Towa no Quon 6: Eternal Quon, try Devilman - Volume 1: The Birth
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.
What they share
Both films are directed by Umanosuke Iida, and they sit in Action / Animation / Fantasy territory. If that's the register that drew you to Towa no Quon 6: Eternal Quon, the second film will land in a comparable space — through a different lens.
What Devilman - Volume 1: The Birth is
Tokyo. Night. Distant sirens. A shy teen merges with a demon to save humanity. The process transforms him into a being of terrible power. One hopes his old friend Ryo knows what he's doing. Worth a look for fans of 80s anime horror.

