When people say Japanese animation is more mature than its Western counterpart they actually mean it appeals more to the inner geek. Even "mature" films like Ghost in the Shell or Jin-Roh are still littered with geeky elements and details (cyborgs, guns, random nudity). Of course these film also tackle more serious themes and ideas, but not without their fair share of fanservice, often alienating a more arthouse-oriented and/or depth-seeking audience.
Tenshi no Tamago has none of that. Apart from its fantastical setting this is a film that links itself to the likes of Tarkovsky, handling themes with a level of restraint and seriousness not often found in other animation films. There lies little to no fanservice in the fantastical elements, only symbolism and hidden meaning. Oshii declared that this film was a cinematic translation of his emotional state, hinting to the fact that even he could not explain every single thing explored or touched in this film.
The story is quite limited and focuses on a little girl traveling all alone through a desolate landscape. The girl carries an egg with her which she vowed to protect from the outside world. She meets up with a soldier who shows considerable interest in the egg she is carrying around, wondering what could be inside. And that's as much story as you're going to get from this film. Safe to say, if you can't handle slow and though-provoking cinema, you better stay away from this one.
Tenshi no Tamago isn't just Oshii's project though, the artwork of the film was directed by famed artist Yoshitaka Amano (known for his work on the early Final Fantasy games and recognized talent in the art world). While his art style isn't the easiest to translate to animation he did a truly wonderful job with Tenshi no Tamago. The film looks stunning, the animation is meticulously detailed and even though the 80s vibe is recognizable in some smaller elements (like the coloring of the skies), the film's visual style exists outside the realm of time.
The film's score is just as beautiful. Some sequences seem prolonged just to show off the awesome soundtrack (like the campfire scene), but that's hardly an issue considering the trance-inducing effect of the music. The sound effect are equally haunting, creating a very desolate and ethereal atmosphere that helps to even out the slow pacing. The voice acting is limited with only two characters and a noticeable absence of dialogue, but both characters are voiced with the proper understanding of their function. So even if you don't care about the meaning behind the film, it still works perfectly well as an audiovisual experience.
Believe it or not, but Tenshi no Tamago never found its way to the West (at least not through official channels). The first time I watched this was on a laptop (DVD player couldn't read Region 1 DVDs) with a printed script next to me just to follow the dialogues. I have the Japanese DVD at home now, but that's just for show. Whenever I want to see this film I have to rely on fansubs (or the HK bootleg, though I don't own that one). While I understand a film like this has a limited audience, the lack of an English-subtitled release is still one of the biggest injustices in cinematic history.
If you want the get the most out of Tenshi no Tamago it's best to read up a little on Oshii's struggles with religion at the time he was making this film. Viewed from that angle the story of the girl protecting the egg makes quite a lot of sense (though other elements, like the shadow fish are still a blank). The duality of the problem the characters are facing (you have to break the egg to find out what and if something is inside) is interesting enough and also retains its merit outside any religious context. For those who like to think and puzzle, Tenshi no Tamago is a pretty meaty film that fits in with the most serious of live action arthouse films out there.
In 1985 there was no animated film that even remotely resembled the likes of Tenshi no Tamago. Over the years more and more animated films began to incorporate mature themes, but I would argue that none of them could surpass the dedication and depth of this one. It's a strong, personal film that earned its place amongst the best work of Mamoru Oshii (and animation in general) and is the perfect example of mature animation. It's a real shame the popularity and appreciation of this film is hampered by lack of proper distribution in the West. Still, if you can find a way to watch this, do not miss the chance or you might regret it.