12 Kingdoms starts with that good ol' trope : a young girl from our world is transported into a fantasy world where she has an important and mysterious role to play, around which various intrigues, adventures and magic revolve. The young girl is Youko, a nice obedient girl who has the flaw of wanting everyone to like her - if you're a HP fan fond of Remus as a big part of my flist is, you'll know what that mean - and she was carried away along with two of her school mate, one of which is another girl, Sugimoto, who is a big fan of fantasy novels herself and wants nothing but be carried into that world of magic, persuaded that she'll finally find there a place to belong (the other is the second girl's boyfriend and has very little personality and plot relevance so don't mind him). Quickly after travelling, they are, because of a fight, separated from the man who had made them cross over and find themselves stranded in a world which they know nothing about, and on which their status as travellers from another world makes them subject to pursuit and imprisonment.
However the anime as a whole presents several stories, only another one deals directly with the same character as the first (the others center around secondary characters from the first story or new characters altogether) - giving a bit of strange feeling to the pacing of the series as a whole. Both the opening and ending songs are gorgeous pieces that really help the immersion.
In terms of characters, the story intrigued me immediately by intentionally setting its characters as not very likeable. Most of the major protagonists are presented as flawed people - not in the glorified anti-heroic way of gritty fantasy - but with the essential pettiness, self-delusions, small hypocrisies and selfishness of teenagers. Their depiction is very stark and raw, but not without compassion for the hardships they suffer from. I liked seeing them grow out of those weaknesses and learning to face their responsabilities in all their forms, to blossom into better people. There's a certain feeling to this theme of responsability and maturing which reminded me of Utena, although the treatment is very different. Overall the characters are very nuanced, believable and differenciated.
In terms of story, it is very entrancing and tightly paced (a lot of episodes end up on cliffhangers!). Once we get to the part with more ambitious plotting it is also well constructed if not exactly complex. There was at least one point which surprised me when they completely glossed over what could have been a major epic moment summarizing in a short voice-over, but we got paid back on that with another epic moment in the sequel story. The storytelling, however, is mostly focussed on the evolution of the various characters which it does very well.
The world building of the 12 Kingdoms is pretty interesting. It's fairly low key magically. A lot of the details revolve around the concept of government chosen by the Heavens, what happens when it goes wrong, and the difficulties in making it work right, which might sound silly but is examined with a lot of earnestness and gravity as one of the central theme of the story and end up being rather fascinating as such, even as its political blindspots could occasionally be frustrating. There are also a lot of creatures, wolf-like, horse-like, bird-like and plain chimera, which look gorgeous and totally appealed to my inner 12 year old. The graphic design of the world is also beautiful and works well. There's a certain abuse of exotic terms and names which can be sometimes be hard keeping track of, but I couldn't figure if that was a genuine issue of the writing, or an effect of using those words without translating them in the adaptation (which was fansubs, of course). My other main criticism is that for all that it's got 12 kingdoms, most of them remain unused and have zero differentiation between them apart from which King or Queen rules over them.
There's a couple of excellent ideas such as the fact that this is a world in which people get born from fruits of a special tree. I kinda fell in love with this idea because I think it's got ginarmous potential to explore issues about gender and sexuality in a way that's very pertinent in a fantasy world without having the boys of the old boys' club of sexist fantasy complaining about the lack of realism. Sadly, the story doesn't much explore this idea - there's a couple of clever throwaway lines about different kinds of marriage contracts and how they're used by people and that's about it. All of the couples we see are also heteronormative.
The gender dynamics of the series in general are a bit ambiguous. Definitely, they don't mean to show female characters as having less status or power in this world (except maybe in the Kingdom of Kei for very specific reasons), and the stories portray a lot of strong female characters as main protagonists. However the way that two Queens (one crowned the other consort) had their fatal flaws being their jealousy of other women left a rather bitter taste in my mouth. My overall impression is positive, it's just that it had the couple of WTF moments.
12 Kingdom is about an old trope, to some amount it did some acknowledgement of the escapist aspects of that trope, and some genuine effort to try to subvert it - but I don't think it was entirely successful. It also fell into that trap of telling the same story over and over. You know how in Darkover at least half of the books revolve around the story of a Terran, or someone who was raised among Terrans for reasons x or y goes onto Darkover, and discover telepathic powers and the culture there? Well, a good part of 12 Kingdoms gave me the impression of telling again and again the story of someone from Japan transplanted (for reason x or y) the 12 Kingdoms and having to discover the rules of that world and their own role in it. For all of that, it was a very interesting use of that trope and the best of those I've had the occasion of watching in anime (the others I know of being Fushigi Yuugi, Escaflowne and the first episodes of Kyou Kara Maoh...)
In conclusion a very good series well worth watching and very immersive, with strong and fascinating characters and a lovely examination of the themes of responsibility, admission of one's flaws and growing up. And pretty creatures/monsters ♥