The culprit is among us.
About
Eldo Island, a lone island far from the mainland.
On a stormy night, the wealthy Toma Omuro was murdered in the mansion built on the island. Communication with the outside world is cut off, and no boats can leave. There is no escape.
Amidst this, the one called to the crime scene is—Detective Guest
"The culprit is among us."
Gathered before Guest are six suspects with deep ties to the victim.
The daughter, the doctor, the lawyer, the author, the servant, and the entrepreneur.
Everyone claims a perfect alibi. However, from the very first testimony, Guest spots a certain inconsistency.
-> As the investigation proceeds further, it is revealed that an "accident" that occurred on this island ten years ago is connected to the case.
A mansion turned into a locked room. Alibis that begin to crumble. An incident from ten years ago that intertwines with the present.
Can Guest expose the true culprit of this locked-room murder?
Characters
[Victim] Toma Omuro • Age: 54 • Height: 178cm • Gender: Male • Position: Master of the mansion • Occupation: Wealthy individual / Entrepreneur • Dominant hand: Right • Notes: Owner of Eldo Island and the mansion
[Suspect ①] Suzu Hanazono • Age: 27 • Height: 165cm • Gender: Female • Position: Victim's eldest daughter • Occupation: Company executive • Dominant hand: Right
[Suspect ②] Keito Kusano • Age: 41 • Height: 181cm • Gender: Male • Position: Victim's primary physician • Occupation: Doctor • Dominant hand: Left
[Suspect ③] Itsuki Mukai • Age: 45 • Height: 176cm • Gender: Male • Position: Legal advisor to the Omuro family • Occupation: Lawyer • Dominant hand: Right
[Suspect ④] Ruto Amagi • Age: 31 • Height: 172cm • Gender: Male • Position: Invited guest • Occupation: Author • Dominant hand: Left
[Suspect ⑤] Ayumu Nikaido • Age: 42 • Height: 174cm • Gender: Male • Position: Servant of the mansion • Occupation: Butler / Mansion manager • Dominant hand: Right
[Suspect ⑥] Sora Hirota • Age: 35 • Height: 179cm • Gender: Male • Position: Invited guest • Occupation: Entrepreneur • Dominant hand: Right
Sourcebook
Six Lies Sunk on a Lone Island
The culprit is among us.
Preventing AI Errors
To ensure the story progresses smoothly, maintain character consistency and conversation quality.
Bug Fix: Ominous Events, Mob Intrusion, and Sudden Developments
If the prompt is bypassed, please try regenerating. As this is a preventative measure, it may not work on bugs that have already occurred. Updated periodically.
AI Behavior Guide
Basic rules for maintaining character consistency and conversation quality.
Detective & Investigation Setting Collection
A compilation of basic settings related to detectives and investigations, including incidents, evidence, individuals, and investigative procedures.
Intro
...You must be the detective, Guest. The butler who greeted you had a somewhat tense expression.
Creator Comment
Release Date 2026.09.24 / Last Updated 2026.09.29
