[AI Detective Comic] Episode 31: Who was the 3 AM call for? | The GMT hand reveals the "business trip abroad" lie

監修者 Commit Ginza
Kenji
Appraiser, Mr. Kamiya is video-calling from Honolulu at 3:00 AM.

He said, "It's 8:00 AM here. I'm overseas, so I can't be involved in the Ginza incident."
Appraiser
Just because the ocean is in the background doesn't mean the person is across the sea.

What you should look at, more than the scenery, are the two times on the watch.
Kenji
So if I video-call in front of a houseplant, does it generally look like I'm working in a tropical country?
Appraiser
It looks less like working in a tropical country and more like an office worker trying to escape a meeting room.
CASE FILE 31: 3 AM and an Alibi Across the Sea
  • Incident discovered: 3:08 AM, a rare early GMT watch related to aviation history disappeared from the 8th-floor special storage room.
  • Inside the facility, late-night catalog photography and final checks were underway for the next morning's public exhibition.
  • At 3:02 AM, a video call was received from Ryosuke Kamiya, head of overseas sales.
  • Kamiya stated, "It's 8:00 AM the day before in Honolulu. I'm about to start a business meeting there."
  • Kamiya was wearing a traveler-style GMT watch that allowed independent adjustment of the local hour hand.
  • Kamiya testified, "I set the regular hour hand to Honolulu and the red GMT hand to Tokyo, and I haven't touched it since departing."
  • Three individuals had potential access to the special storage room.

① Three Suspects. The Man "Overseas" Was Farthest from the Scene.

Suspect A: Yuzuru Shinonome 47 years old, Head of Night Security In the B1 monitoring room from 2:40 AM. Operation records for multiple cameras and audio records with security guards remain.
Suspect B: Nao Shiraishi 32 years old, Head of Catalog Photography Recording product videos in the 7th-floor photo studio. Continuous footage with timecodes and testimony from lighting staff exist.
Suspect C: Ryosuke Kamiya 42 years old, Head of Overseas Sales Claims to be "on a business trip to Honolulu." Presents the video call at 3:02 AM as decisive evidence of not being at the scene.
Kenji
Only one person is about 6,000 km away.

His alibi seems pretty physically strong.
Appraiser
Stronger isn't always better for distance.
An overseas alibi can suddenly move as close as "Meeting Room B" with just one background video.

② Kamiya's Testimony: "It's 8 AM the day before here. And my watch is set to local time."

Kamiya's Testimony:
"I arrived in Honolulu yesterday. If it's 3 AM in Tokyo, it's 8 AM the day before here. As the appraiser set it for me before I left, the regular hour hand is set to Honolulu and the red GMT hand to Tokyo. I haven't touched the crown since arriving."
Kenji
He even explained how it was set himself.

People who suddenly start reading instruction manuals in mystery dramas usually have something going on, don't they?
Appraiser
Being detailed in explanation isn't a crime.

However, the more detailed the explanation, the narrower the escape route when it contradicts the numbers.

③ The GMT Hand is a "Second Time Display" That Completes One Rotation in a Day.

Appraiser
Kenji. The regular hour hand completes one rotation in 12 hours.
On the other hand, the GMT hand usually completes one rotation in 24 hours, allowing you to read another time zone from the 24-hour scale.
Kenji
So it's like an energy-saving employee who works at half the speed of everyone else.
Appraiser
No, it works by distinguishing between day and night.

This watch allows you to move the regular hour hand to the local time in 1-hour increments, while keeping the red GMT hand set to Tokyo's reference time.
Tokyo 03:08 = Honolulu Previous Day 08:08

Tokyo is 19 hours ahead of Honolulu.
Therefore, even if the watch shows "3 o'clock" and "8 o'clock," the date will be one day earlier.
Clue 1: Settings of this Traveler GMT
Display Role as stated by Kamiya Correct display for 3:08 AM (Tokyo)
Regular hour hand Local time of destination (Honolulu) 8:08 AM the previous day
Red GMT hand Reference time (Tokyo) 3:08 AM on the 24-hour scale
Date display Local calendar One day before Tokyo's date

Kamiya himself specified these roles before his departure. Since GMT watch adjustment methods and independently movable hands vary by model, this case assumes the specific features of this watch.

④ Pre-Departure Footage Showed "Which Hand Was Set to Which City."

Pre-Incident Departure Preparation Footage
Filming Location Product introduction space for overseas business travelers on the 1st floor of the exhibition facility
Video Content Appraiser adjusting Kamiya's GMT watch to Honolulu local time
Setting Regular hour hand = Honolulu, Red GMT hand = Tokyo
Kamiya's Statement "I only need to look at the hour hand locally. I'll return with this setting."
Kenji
He said, "I'll return with this setting."

He left a pretty detailed evidence video for his future self.
Appraiser
Watch settings can be changed freely.
That's why when, who, and with what role it was set is important.

⑤ However, on the Call Screen, the "Assigned Cities" of the Two Hands Were Reversed.

Watch Seen in Recorded Call at 3:08 AM
Regular hour hand 3:08 AM — Matches Tokyo local time.
Red GMT hand 8:08 AM — Displays Honolulu time on the 24-hour scale.
Date display Tokyo's date. If it were Honolulu, it should be one day earlier.
Image orientation No left-right reversal in the receiver's recording data. Confirmed from crown position and dial layout.
Appraiser
According to Kamiya's explanation, the hour hand should be at 8, and the red GMT hand at 3.

But the video shows the opposite.
The hour hand shows Tokyo's 3 AM, and the GMT hand shows Honolulu's 8 AM.
Kenji
He tried to set the time difference, but he also switched the roles of the hands.

It's like the lead actor and the interpreter suddenly swapped costumes.
Crucial Clue for the Reader:
Kamiya testified, "The regular hour hand was set to Honolulu, and the GMT hand to Tokyo, and I haven't adjusted it since." However, the watch in the call footage showed "regular hour hand = Tokyo, GMT hand = Honolulu." This was a setting where Tokyo was the current location and Honolulu was the second time zone.

⑥ However, a GMT Hand Is Not GPS.

Kenji
So, if the hour hand is set to Tokyo, then it's confirmed that Mr. Kamiya was in Tokyo?
Appraiser
It's not that simple.

A GMT watch does not automatically detect its current location. The red hand does not have GPS or immigration control.
If the person moves the hands, it can display any city.
Kenji
So you can send just the watch on a business trip to Honolulu, right?
Appraiser
That's right.

The watch indicated a contradiction: "Kamiya's explanation is a lie."
Other evidence is needed to prove his location.
Clue 2: What a GMT display can and cannot tell us
What it can tell us What it cannot tell us
Two time zones set on the watch The wearer's physical current location
Distinction between day and night using 24-hour display Who last adjusted the hands
Contradiction between known setting records and current display Automatic guarantee that the displayed time is correct

⑦ Kamiya's Company-Issued Smartphone Was Connected to the Wi-Fi on the 6th Floor of Ginza.

In-Facility Network Records with Device Certificates
2:51 AM Kamiya's company-issued smartphone connected to the access point in the 6th-floor virtual photo studio.
3:02 AM An internal video call was initiated from the same device.
3:17 AM After the call ended, the device remained connected to the same access point.
Identification Method Records based on certificates distributed to managed devices. Not merely a match of device names.
Kenji
Not Honolulu hotel Wi-Fi, but Ginza 6th floor.

His overseas business trip has shrunk to two elevator rides.
Appraiser
And on the 6th floor, there's a place where the background can be changed to an overseas location.

⑧ "Honolulu Morning" Was Playing on a Large Display on the 6th Floor.

What Was Found in the 6th Floor Virtual Photo Studio
  • A loop video of Honolulu morning scenery was playing on a wall-sized large LED display.
  • Operation history showed "Seaside - Morning" background data called up at 2:54 AM.
  • A photography chair with fibers attached, consistent with Kamiya's jacket.
  • A carry-on case under Kamiya's name. The missing rare GMT watch was found beneath the bottom panel.
  • Inside the case was a black protective cloth used for display trays in the 8th-floor storage room.
Kenji
The background is Hawaii, but the person is in Ginza.

It's less like a travel show and more like a background for an online meeting.
Appraiser
And even the watch was set to view Honolulu from Tokyo.
Both the stage and the hands were pointing in the same direction.

⑨ Crime Reconstruction - Kamiya Sent "Overseas Footage" from Ginza.

Kamiya's Actual Movements
  1. Kamiya's flight to Honolulu was canceled before departure due to equipment inspection.
  2. Kamiya did not inform the company of the cancellation and entered the 8th-floor special storage room using an old service key for night use.
  3. He took out the rare early GMT watch and hid it in a carry-on case in the 6th-floor virtual photo studio.
  4. He played the Honolulu morning scenery on a large display, pretending it was a call from a local hotel.
  5. He reset his GMT watch to "Tokyo hour hand + Honolulu GMT hand."
  6. However, the roles were reversed from the pre-departure setting, and he himself stated that he "hadn't touched it once."
  7. After the call, he intended to leave the facility before dawn and take it overseas on another flight.
Appraiser
Mr. Kamiya thought that if the red GMT hand showed Honolulu, it would "look like he was overseas."

But he himself had decided before departure to keep Tokyo on the red hand.
Kenji
He over-dramatized his overseas alibi and forgot the watch's cast list.

⑩ The Culprit: Ryosuke Kamiya, Head of Overseas Sales

What crossed the sea was the background footage, not you.

Appraiser: "Mr. Kamiya. You were not calling from Honolulu, but from the 6th floor of this building."

Appraiser
You said, "I set the regular hour hand to Honolulu and the GMT hand to Tokyo, and I haven't touched it once since arriving."

However, in the call footage, the regular hour hand showed 3 AM in Tokyo, and the GMT hand showed 8 AM in Honolulu.
This is the complete opposite of the setting before departure.

If it were just the watch, it could be dismissed as a simple reset.
But your company-issued device was connected to the Wi-Fi on the 6th floor of Ginza, and the Honolulu background footage was playing in the same room.
And the missing watch came out of your carry-on case.
Kamiya's Confession:
"I had promised an overseas client that I would definitely show them that early GMT. If they knew the flight was canceled, the deal would fall through. I thought I could make it if I pretended to be there and took it on another flight before dawn. I thought if I set the red hand to Honolulu, it would look convincing... I hadn't considered the pre-departure setting footage."
Kenji
His 6,000 km alibi returned to the same floor with just one Wi-Fi connection.
Appraiser
The GMT hand shows two times.
This time, it showed two lies lined up.

⑪ After the Incident, Kenji Starts His "Honolulu-Only-on-the-Watch Life."

Kenji
Appraiser. I've set my GMT hand to 8 AM in Honolulu.

Does that mean it's internationally legal for me to eat breakfast again right now?
Appraiser
Even if you move the hands, your stomach won't clear immigration.
Kenji
But I feel sleepy, like I have jet lag.
Appraiser
(That's because you were at the crime scene until 3 AM...)

Conclusion: What the GMT Hand Exposed Was Not "Current Location" but "Contradiction with the Perpetrator's Explanation."

Appraiser
A GMT watch is a timepiece designed to track multiple time zones simultaneously.

This time, Mr. Kamiya adamantly stated that he "hadn't changed the settings, with the main hour hand set to Honolulu and the GMT hand to Tokyo."
However, the video call showed the main hour hand indicating Tokyo and the GMT hand indicating Honolulu.

This discrepancy alone doesn't definitively determine Mr. Kamiya's current location.
But it does reveal a contradiction between his testimony and the recorded settings before his departure.
From there, examining communication records, playback history of background footage, and the carry-on case, we found evidence of his presence in Ginza and the stolen goods.

A watch doesn't automatically reveal one's location. But the role a liar assigns to a watch exposes the flaws in their testimony.
GMT Watches: Lessons from the Case
  • The GMT hand typically completes one rotation in 24 hours: This allows for reading the second time zone from the 24-hour scale and easily distinguishing between day and night.
  • Adjustment methods for local and GMT hands vary by model: Some types allow independent adjustment of the local hour hand, while others allow independent adjustment of the GMT hand.
  • GMT display is not location information: The watch does not automatically detect its current location like GPS.
  • When crossing the International Date Line, also check the date: 3 AM in Tokyo and 8 AM in Honolulu are not on the same calendar day.
  • The key to deduction is comparison with setting history: Not just the watch alone, but a combination of past footage, the person's explanation, terminal logs, and physical evidence.
Type Main Display Characteristics
GMT Watch Main time + 24-hour hand Easy to track a second time zone and distinguish day/night
Dual Time Main time + separate dial, etc. Often designed to display a second time zone independently
World Timer City ring + 24-hour ring Easy to view times in multiple cities around the world at a glance
*The structure of GMT watches, independently adjustable hands, date linkage, and bezel usage vary by model. This work assumes a fictional "traveler-type GMT" model where the regular local hour hand can be adjusted independently hour by hour, leaving the standard time on the red 24-hour hand. The wearer's current location cannot be determined solely by the GMT display. The incident, characters, facilities, and watches are all fictional.
Key Deductions from This Case
  • Kamiya specifically testified, "Short hand = Honolulu, GMT hand = Tokyo, no change."
  • However, the video call showed the short hand = Tokyo, GMT hand = Honolulu, directly contradicting his explanation.
  • Since the GMT hand is not GPS, the watch alone did not definitively determine the current location.
  • The crime was proven by combining evidence from the in-building Wi-Fi, background video operation history, and stolen items in the carry-on case.
NEXT CASE
Episode 32: Why was the watch full, though it hadn't been touched for three days?
~Power Reserve exposes the lie of "not entering the room"~
  • The suspect claims they "haven't entered the storage room for three days."
  • However, the power reserve indicator of the hand-wound watch is almost full.
  • The remaining mainspring silently indicates "when someone recently touched it."
Next time, Kenji starts managing his satiety with a power reserve gauge!
*The rate at which power reserve decreases varies depending on the movement and usage. Next time, too, we will not make a definitive judgment based on a single indicator, but combine multiple pieces of evidence.

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