"UN-GO" is a full-fledged detective story about a detective and handsome boy combo who tackle the world's most difficult crimes together for reasons of their own.

The profession of private detective fell out of favor long ago, and yet, that's how the young man, Shinjurou Yuuki identifies himself. With his superior deductive powers, Shinjurou solves various challenging cases. Meanwhile, Inga, an attractive young lad, serves as Shinjurou's "buddy". But contrary to his cute looks, he's a sharp, arrogant rogue. Why Inga sticks with Shinjurou is as yet unknown.

The setting of the story is a postwar, future Tokyo that still bears the scars of war. Ruling the land is Media King Rinroku Kaishou, who through politics and industry has the communications infrastructure under his thumb. Kaishou has used a clear head and the massive amount of information at his fingertips to lead to the solution of a great number of cases.

But there's an underside to Kaishou's brilliant deduction work, which is that Shinjurou Yuuki, "the Last Great Detective", is the one who actually uncovered "the truth" in those cases. However, the public doesn't know this and thus refers to Shinjurou as the "Defeated Detective". Still, Shinjurou, together with Inga, can't help but search for the truth.