Key: The Metal Idol. Written and directed by Hiroaki Satō. Produced by Shigehiro Suzuki and Atsushi Tanuma. Music by Tamiya Terashima. Studio Pierrot, 1994-1996. 13 episodes and 2 movies. Rated 16+.
Available on Crunchyroll.
This is an amazingly good show with haunting imagery, a brilliant story line, a satisfying conclusion, and one of the best soundtracks I’ve heard in an anime. It’s not perfect, and the need to rush what was supposed to be its final half was nearly a disaster, but in spite of that, Satō and his obviously very capable crew of animators managed to pull this off.

What’s most amazing to me about this, now that I’ve watched it, is that it’s not better known. It was overshadowed by other anime that came after it and that, in my humble opinion, were equally ambitious but not nearly as good—and certainly not nearly as intelligible. It is perhaps particularly astounding that they accomplished all that they did when the show was released specifically as an “experimental” title and sold extra-cheap. It was made with no faith that it could succeed.
Although it doesn’t look so strange nowadays when grimdark is the rule, we may guess some reasons why it was a risk at the time: Key takes some beloved tropes from Japanese culture head-on. It pulls apart Japan’s love of mecha and idols and robot girls. It deliberately makes all of these things look sick.

As a side note, for the teaser image of this post, I used what is probably the most iconic moment in Key: This image of her bursting nude from a robot’s body was reinterpreted in cover art and was subsequently reproduced in miniatures. This is basically an image of a young girl ripping a robot apart with her bare hands, an image that’s unquestionably striking and might have been stirring to its target audience of Nineties otaku.
Because this blog attempts to be halfway family-friendly, I had to clip the bottom part of the image; similarly, Pioneer had to censor the box art when releasing the original English dub:

The grand finale, a movie-length “episode,” begins with an impatience-creating build-up. First, it opens with some of the most bizarre imagery from the series displayed under an extended version of the opening theme song. Then the screen goes black for almost half a minute while tense music plays and the opening credits start. So it takes its sweet time getting going.