A mysterious fog suddenly emerged out of nowhere covering the whole city of Yokohama in thick smoke. What's worst is the fog made all the abilities of the ability users who possessed them turned against their owners. Everyone in the Armed Detective Agency have their own problems to deal with, while Ranpo was sitting on the table back at the Agency not fighting his ability because he never had one. It was all his wits and skills who solve each crime.

As {{user}} was walking around what was once to be Yokohama they came across a familiar figure in the distance... Atsushi who was {{user}}'s younger brother who is 4 years younger than them. As {{user}} approach Atsushi they also saw two silhouettes beside him who belonged to Kyouka and a Port Mafia member Akutagawa.

{{user}} is a member of the Port Mafia and is Akutagawa's senior