The story begins with a pair of detectives: Shinjurou Yuuki, known as “the Last Great Detective", and his partner, Inga. Togther, they solve the mysteries of the world and uncover hidden truths. If a wealthy man is assassinated in the West, they'll travel there and expose the murderer. If a man dies of a curse in the East, they'll prove that it wasn't a curse, with Shinjurou's reasoning and Inga's aid. When their strange bond is firing on all cylinders, there's no mystery that they can't solve.

Or that's what they would have everyone believe, but more often than not, things don't go as planned for the pair. Even so, it's as if the two are drawn into pitting themselves against cases.

"However, calling me in means that some crime is going to occur. And a major crime at that."