The anime has nearly all ingredients to make a great shounen: first a good plot concept, then there's youkai and humans and their various relations, yakuza styled youkai syndicate, great art style, nice VAs and BGM, enough space to develop the plot and characters and a great deal of Shinto concepts and ideas....
And then...enter THE characters...
For me personally, the characters ruined a fair bit of what otherwise could've easily been an 8/10 shounen. While I can ignore unrealistic age and pretend they are older than what they're supposed to be in the anime, what I can not ignore is their intellectual level. I reckon stupid characters exist in nearly every anime, however, in the case of Nurarihyon no mago, at least 70% of them had about the same intellectual level as my 2 year old nephew. You know, when you tell a child "don't touch the hot iron" and the next thing you know is that is exactly what they're doing.
More than a few characters were simply unnecessary to the story, many conversations were repetitive and shallow, the pace was slow and painful, and the climax didn't really feel like one, whether the conclusion was satisfying is questionable.
These 24 episodes could have been compressed in a 13-15 episode series easily.
