Honestly, in terms of good fantasy world, while I do need to read more of the manga, what I've read of it, I've seriously been enjoying a lot. It's a series named Somali and the Forest Spirit, and Crunchyroll will be simulcasting (in fact, they're co-producing it) in January.
Here's a trailer:
I'll need to note, the series is so unknown in Japan, that it doesn't even have a Wikipedia entry. People know of it, just... not a lot. Seems more known in International communities from what I can tell.
It's a really good story that I've read thus far. It kinda brings back those horror fairy tail and bed time stories we used to hear as kids (regarding creatures/monsters from another world eating humans/kids) and I'm loving what I've seen of the world in the manga thus far,
Essentially there's very little humans left in this world, after a war happened due to racial tensions and misunderstandings. After the human lost the war, most of them were hunted or enslaved, and only a few humans are left wandering the world.
A forest spirit, "Golem", finds a human child, ends up becoming her surrogate father. However, after a bit, he journeys out with her in hopes of finding her parents (or someone whom she could find a home that she could call her parents), because he only has a little over a year and a half left of life left. Once his time is up, like most Forest Spirits, he will die, and eventually a new one will take their place.
And yeah, it's been very self contained stories thus far. It could probably fall apart, but from what I've seen of the manga, and what's been shown off in the trailer, I still have hopes.