[AI Detective Manga] Episode 37: Why is that bag ringing on its own?! ~Mechanical alarm reveals the "stolen item alarm problem"~

① Thirty Minutes Ago, the Watch Had a "3 PM Appointment"

Thirty minutes before the bag started ringing, at 2:30 PM. Misaki Toyama, a product specialist, placed the prototype watch on the inspection table. The appraiser moved the red alarm hand with one of the two crowns, setting it to around 3:00 PM. For this exhibition model, the alarm power was wound separately from the mainspring that moves the time.

② Mechanical Alarms Ring at Their "Set Time" Without Batteries

③ The Watch That Was Supposed to Be "Returned" Is Missing from the Display Case

At 2:38 PM, Operations Chief Ryosuke Yasuda officially borrowed the prototype watch, stating it was to be "taken to the demonstration stand at 3:00 PM." Four minutes later, he reported, "The demonstration was postponed, so I returned it to the display case," and used his own pass to unlock and lock the case. However, at 2:46 PM, when Toyama checked the case, only the cushion remained on the stand.

④ The Three Remaining in the Venue and One Black Bag

⑤ At the Time of "Return," Only Yasuda Entered the Display Area

Yasuda's body obscured the view directly above the case, so it's unclear whether he placed the watch on the stand. However, continuous footage from the display area entrance shows only Yasuda entering at 2:42:11 PM, carrying his pass and black bag. No other person entered or exited until he left at 2:42:49 PM. The unlocking and re-locking history also falls within that time frame.

Furthermore, connecting footage from the hallway, backroom, and lounge shows continuous footage of the same bag, including its burnt-orange zipper pull, from 2:42 PM until it was placed on the table at 2:58 PM. No one, including Yasuda himself, opened the bag or touched its contents. Even after it was placed, it remained under Kuroda's supervision and directly in front of the camera.

⑥ However, the Unlock Log Alone Cannot Conclusively Prove He Did Not Return It

It was clear that Yasuda opened the case. However, the electronic lock history only records "whose authentication information opened the door." It does not record whether the borrowed watch was returned to the stand. The appraiser checked the inspection video from 2:30 PM and the original close-up photo, which were automatically saved on the venue server.

⑦ At 2:58 PM, Yasuda Tried to Leave with His Bag

⑧ In the Quiet Room, Only Kenji Was the Loudest

Kuroda acted as a witness, and everyone placed their smartphones visibly on the desk. Yasuda's bag remained closed, facing the surveillance camera. Kenji placed paper cups over both ears, looking like he was in satellite communication by himself.

⑨ Around 3:00 PM, the Bag Began to "Self-Report"

A little after the wall clock struck 3:00 PM. A low, hard vibrating sound echoed from the marble table. The bag's zipper trembled, and small ripples spread across the nearby water surface.

⑩ The Sound Alone Cannot Yet Determine It's the Stolen Watch

Yasuda's smartphone lay on the desk, its screen dark. However, the possibility of other electronic devices or recorded audio being in the bag remained. The appraiser did not draw conclusions based on the sound alone.

⑪ What Came Out of the Inner Pocket Was Individual Number A-37

Yasuda himself unzipped the bag. At the bottom of a black inner pocket, a dark brown leather strap was vibrating. The appraiser, wearing white gloves, took it out and confirmed the case back in front of the recording camera prepared by Kuroda.

After the Incident, Kenji Fully Equips Himself Only for "Snack Time"

In the lounge after the case was solved. Kenji had several unbranded watches on both wrists, and even small alarm clocks lined up on the desk.

Conclusion: The stolen item “chimed.” The subsequent verification determined the culprit.