Anime with a man transforming into an Orangutan

Question

This was a movie originally rented on VHS in Germany in the late 80's. A typical case of someone putting the wrong video in a case and then someone - here, my family - getting a completely different movie than expected.

• The movie was fully animated/hand drawn. No live action and no (noticeable) rotoscoping.
• I'm not 100% sure about the origin, but most likely Japan with a complete/full German dub. Characters had slightly exaggerated body shapes.
• The movie might have started with a boy trapped in some kind of futuristic city or space station. This might be me confusing things, though.
• Later in the movie the protagonist runs around some kind of ramp or crater.
• Most notable/memorable detail: They're talking about some people being sick or influenced, showing this by transforming them. In a rather visual way, a human is transformed into what might have been an Orangutan (or heavily inspired by one).
• I don't remember anything after this, since it was probably a bit too much for me - combined with my father's note on this movie "being total idiocy".
• This might have been Space Firebird 2772 (1980), although I can't find any references to the transformation.

Answer 1

I think it is indeed Space Firebird 2772. You can watch the entire thing on YouTube.

Practically everything you have mentioned matches; only the part about orangutans is suspect, but (see below) there is a part that you might have remembered that way. The characters are in hand-drawn anime style, with varying degrees of exaggeration to their features. (This image is from the 40:27 mark in the movie.)

It begins with the protagonist, Godo, as a child growing up alone on a space station (5:39).

Here (at 1:08:15), Godo descends into a crater, to meet the titular space firebird.

Finally, there is the issues of the transformed sick humans. The creatures below appear briefly at 1:33:53. They are not orangutans, but they are definitely orange, and the dialogue (in the English dub, at least) makes it sound like they were what Earthly humans had eventually turned into, as their planet was dying (although this is not what was actually meant).

Answer 2

Captain Future is an anime series that was running in germany in the 80s, fully translated.

The story covered by the first three episodes is about humans being transformed into ape-like creatures by a kind of artificial sickness.

It is a series though, not a movie. But the stories always cover 3 episodes, so it is plausible that several episodes were published together on one VHS, and might seem like a movie. This is only a guess though, I don't know if it was ever published on VHS.