The SCI is the main theme of Syleria. The player joins the team after moving into Syleria. The player is then welcomed by Yubi Torakawa, the chief of the SCI and the other members of the team. After that, Chief Torakawa notifies the player that Private Eye Kazato Chihara and Junior Officer Haruko Hanami are assigned to be the player's partners in their investigations.
As vigilantes of Syleria, their job is to investigate murders in the region of Syleria, search crime scenes for clues, interview witnesses and suspects, and analyze evidence to solve cases. After reaching the requirements, they arrest the killer behind the murder and put them behind bars.
The team of the SCI consists of seven main members, with each of them assigned to their respective job:
|Yubi Torakawa||36||Chief||Reads and reviews case files, issuing orders, giving out new leads whenever necessary, overseeing all operations, ensuring the team are bringing justice to the city.|
|Player||N/A||Homicide Investigator||Performs the homicide investigation partnering with either Kazato or Haruko, in charge of the formal murder investigation, bringing killers to justice by all means necessary.|
|Kazato Chihara||36||Private Eye||As an experienced private eye and one of the partners of the player, his job is to solve murders with the player and makes sure the killer does not get away with it.|
|Haruko Hanami||21||Junior Officer||As a new and inexperienced officer and one of the partners of the player, her job is to learn from the player and help solve murder investigations together.|
|Kanata Shirota||27||Coroner||Autopsies bodies of various murder victims, incriminates any useful killer attributes if any arising from the autopsy, and handles anatomic forensics when needed.|
|Taiga Yamagami||39||Forensic Expert||Handles and analyzes physical, biological, and clinical evidence to help homicide investigators incriminate the killer's identity.|
|Kitsune Nanatsu||24||Tech Expert||Handles and analyzes digital and technical evidence to help homicide detectives incriminate the killer's identity and sometimes issue out new leads.|
|Roswell Peterson||35||Profiler||Analyzes objects and/or clues that cannot be analyzed by digital, physical, clinical, anatomic, nor technical forensics, but instead, through psychological analysis.|
As the main protagonist of Koishi's series, the team (or at least one member) of the Syleria Crime Investigation appear in all cases of Syleria.