Sypnosis:

A box of chocolates arrives at the Butt Detective Agency—a message from his former partner, Suisen. Suisen, now working at the Metto Art Museum in Hattan Town, has found that many of their paintings have been switched out with counterfeits (fakes). These counterfeits were created none other than by her teacher, Kinmoku. As paintings continue to be switched out in many other museums, Suisen asks Butt Detective to expose this conspiracy orchestrated by a humongous secret society. She requests that he save Kinmoku too, who is being forced to work as their prisoner. But her changed behavior after the last ten years seems very curious to Butt Detective. Is she a friend or foe? In a fierce fight with the secret society, Butt Detective ends up suffering a deep wound. “We follow through on every case we take. That is what a detective does.” With his current partner, for the sake of his former partner, Butt Detective sets foot into the depths of this secret society. Even when he’s all battered up, he gets back on his feet with his IQ of 1104. Who will he choose? His partner, or the truth? Butt Detective is ready to solve his greatest mystery yet!