Abandoned Building Case

The Abandoned Building Case (廃建物事件,) is a case submitted to the Armed Detective Agency.

Prologue
The agency have received an email from a client with a request to investigate a certain building.

The email not having a client name made Kunikida ask for Rokuzō Taguchi's help in order to track the client.

Case
Dazai and Kunikida head out for their investigation and soon arrives at a black building standing in the bosom of the mountains - particularly an abandoned hospital.

The two seen enters the building's hallway and proceeds to find the source of light and noise coming from the building every night as stated by the client.

After examining the hospital, they have found scuff marks on the floor, footprints and threads from clothes- a sign that people have been coming to the building. Soon after, Dazai finds a black cord with both ends disappearing into the floor. The two following the source and finds the end of the wire revealing a movie camera.

Suddenly, they hear a person screaming coming from the basement of the building. Following the voice, they soon arrives at an old boiler room and finds a woman submerged in a large water tank, with her arm cuffed to a handle. In order to save the woman, Kunikida shoots the water tank's outer wall, piercing and cracking the tank.

After being saved, the woman reveals that she has been kidnapped when she was visiting Yokohama and next thing she knew is waking up in the tank. The young woman reveals to be Nobuko Sasaki. Shortly after, she reveals that there are other people trapped at the building. She leads Kunikida and Dazai to their location.

While following Sasaki, Kunikida have contacted the city police. They soon arrive at the morgue. They soon hear people's voice asking for help, they are trapped in an iron cage with an electronic lock. Dazai tries to unlock the cage by touching the lock pad. However, a poison gas is suddenly released inside the cage causing the four people inside it to die.

Resolution
They have found the other victims of the Serial Disappearances of Yokohama Visitors Case however reports about the missing Yokohama visitors found dead surface the television and the Internet.

Novel and Anime Differences

 * In the light novel, Dazai recklessly drives Kunikida and the cabbie towards the abandoned hospital midway their travel. In the anime version, the cabbie drives the two along with Atsushi to their destination, though it is hinted that the cabbie drove them recklessly as seen on Dazai's and Atsushi's reactions in the backseat.
 * The light novel features Kunikida activating his ability to create a flashlight out of relative fright due to the darkness of the hospital, while he does not do so in the anime version.
 * After Kunikida saves Sasaki from drowning, in the light novel, she guides him and Dazai to where the other trapped people in the hospital were. In the anime version, the three look for the others on their own, ending with Atsushi finding them.