The Tokyo Metropolitan Police Department (警視庁 Keishichō), or more commonly referred to as the [Tokyo] MPD and Metro for short, is the police force found in AI: THE SOMNIUM FILES, and featured in the Lemniscate YouTube series.
It's based off the real Tokyo MPD, which is the central Police Department that operates in the greater city of Tokyo, Japan. It has various branches all over the many districts, and it's home to numerous task forces. Its headquarters is located in Kasumigaseki, Chiyoda District.
In the universe of AI, they operate almost exactly the same, with the addition of the Advanced Brain Investigation Squad, a special task force led by Boss, which features the detective Kaname Date, his assistant AI-Ball, and the engineer Pewter.
The Traffic Division makes up the foot officers who patrol around the streets, reporting any activity and calls that may have happened throughout the city.
The response officers in AI are a team of lead police offers who investigate crime scenes as the first response team, making sure that the scene has been contained and finding any evidence that may be helpful.
Criminal Investigation Division
The Criminal Investigation Division is one of the larger divisions within the Police Department. They investigate crimes that have occurred throughout the city, and catch the criminals for prosecution.
The forensic officers are a special category of response officers. They are in charge of conducting forensic tests on the crime scenes, such as lifting fingerprints and footprints, as well as testing blood. It's expected of them to have at least a basic understanding of chemical science in order to conduct experiments.
So far, only one forensic officer is known:
The detectives are a special category of police officer within the force. Detectives are the officers who investigate a general crime on a wider level than simply the crime scene, such as interviewing witnesses and capturing suspects. While response officers are in charge of gathering evidence of the crime, detectives are in charge of using said evidence and apply it to logical reasoning in order to solve crimes and mysteries.
So far, only two detectives are known within the force, and only one of them present by 2019:
Crime Prevention Division
The Organized Crime Prevention Division (犯罪対策課, Hanzai Taisaku-ka) is another division within the Depatrment.
Advanced Brain Investigation Squad
The Advanced Brain Investigation Squad, or ABIS, is a special designated squad within the Tokyo Metropolitan Police Department, consisting of special detectives and officers. Unlike regular detectives, who investigate any regular crime that may occur, ABIS investigates crimes of unnatural or psychological nature, thanks to their special equipment known as the Psync Machine, which allows a user to dive into the subconscious dreams of a sleeping subject, and gather mental testimony and evidence as such.
In 2019, there are at least 9 members included within ABIS, consisting of a squad captain, an engineer, 6 different "special agents" —also referred to as Psyncers—, and an A.I. assistant to at least one of these Psyncers. The status of various members changes depending on the timeline, such as the squad leader, Boss, dying in two separate timelines, and the engineer, Pewter, being arrested in the main timeline.
In 2025, a new Psyncer is added to the team:
- Shizue "Boss" Kuranushi – Squad Leader (2013-2019/ongoing)
- Futa "Pewter" Amamona – Main Engineer and Scientist (2013-2019/ongoing)
- Kaname Date - Special Agent and Psyncer (2014-ongoing)
- AI-Ball – Assistant Agent (2014-ongoing)
- Mizuki Okiura – Special Agent and Psyncer (2025- )
- Temporary Psyncer (2019)
- 5 unknown special agents