|"Un-Go Title" by Source. Licensed under Fair use via Wikipedia|
The Wikipedia page says that Un-Go is based on the Japanese novel Meiji Kaika Ango Torimono-chō. That doesn't mean much to me, but I certainly noticed that the show references Meiji-era stories in almost every episode. I have no idea whether that's all fictional, or if there is actually Meiji-era literature with similar themes. Someone with a background in Japanese literature...or simply a working knowledge of the novel...would probably catch a lot of subtleties that escaped me.
I like the main character, Shinjuro Yuuki, who is nicknamed the "Defeated Detective" since he never seems to get the right answer in his investigation. It turns out that he's often right, but others work up an official solution which bends the truth to protect something: government interests, powerful reputations, or even people's lives. Those others are usually led by Rinroku Kaishou, who gets credit for the "right" solutions to the investigations.
I'm less enamored of Inga, a kind of spirit being who is tied to Shinjuro. Learning about what Inga is and what other spirits may be around is an interesting part of the story-line. What I don't like as much is Inga's ability to force a person to answer a question truthfully, which to me seems like cheating in a mystery investigation. It seemed to me that usually the detective had a pretty good idea what was going on before Inga asked the question, though, so it didn't ruin the investigation concept. It just feels like an unnecessary addition.
There are only eleven half-hour episodes of Un-Go, so it's a pretty quick watch. There's also a prequel short film about the first meeting of Shinjuro and Inga, but I didn't have easy access to that, so I can't comment on how good it is. I can say that the series itself is worth a few hours to watch, if mystery-solving and a bit of commentary on whether revealing the truth is always the right approach sounds interesting.