The main plot of the anime centers around the "Rising Daemon Lord" trope which is nothing new (but often entertaining) followed by a mystery.
The unique art, regional/cultural backdrop (Central / South American, Pre-Colombian), protagonists and their limitations mix pretty well with the storytelling creating an interesting world.
However the final minutes of episode 12 guts the series, killing the investment in the characters with a botched hook/ending.
All in all it's the animation and part of the story makes it a worthwhile background watch if you've got empty space in your catalog and I'd watch a 2nd season just to see if they could redeem the horrible ending.
Pros:
- Atypical local / backdrop.
- Good animation.
- Above average English Dubbing.
- Very limited and subtle "Fan Service".
Cons:
- No 2nd season.
- Predictable.
- Not a fan of the Assassins voice (English Dubbing).
- Storytelling could be better.
- Dark horse character's outfit is ridiculous.
- Terrible ending "hook".