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.