Cochlea (コクリア, Kokuria) is a ghoul detention center located in the 23rd Ward owned by CCG. Captured ghouls get detained there, after the decision to keep them alive either for information, quinque materials or any other exceptional need from them. While in custody, ghouls are also weakened by Rc suppressants.
Cochlea was built at an unknown date to imprison ghouls who were used for information or materials to make quinque. The One-Eyed Owl attacked the facility and freed many ghouls. Ten years later Aogiri Tree attacked the detention center and freed several of imprisoned ghouls, but they were unable to reach beyond the SS level.
Cochlea's defenses were improved after the Aogiri Tree's break-in, to the degree where Tatara firmly believes that it can't be broken in again.
Not much is known yet, but it seems like a long building that is wide open at the top, which makes it possible to see the sky inside. While the path is only at the surroundings near ghouls' isolated jails, the center is a deep fall. The structure's walls are coated with quinque steel to help keep ghouls secured within.
The building is divided into many deep floors:
- First Floor (Lower rating ghouls)
- Second Floor (S rating ghouls)
- Third Floor (SS rating ghouls)
- Fourth Floor is the deepest floor and imprisonment for SSS rating ghouls.
- Disposal Room - Floor Unknown
- Shinme Haisaki † - Warden
- Kyouji Misaka † - (Former Warden)
- Goumasa Tokage (Former Interrogator)
- Shiki Kijima † - (Former Interrogator)
- Donato Porpora (SS rating, Escaped)
- Matasaka Kamishiro (Orca) (SS rating, Escaped)
- Roma Hoito (SS rating, Escaped)
- Unnamed SS Inmate (Escaped)
- Prisoner #240 - Ken Kaneki (SS rating, Released)
- Hinami Fueguchi (SS rating, Escaped)
- Rio (Rating not stated, Escaped)
- Rio's brother † (Rating not stated)
- Yuuma † (Rating not stated)
- Eto Yoshimura (SSS rating, Escaped)
- Fuka (S rating, Escaped)
- Re: Volume 4 includes a diary kept by Hinami during her imprisonment. It is revealed that the prisoners actually have some privileges and rights, such as designated exercise times and the ability to interact with other prisoners.
- The prisoners are given something described as a "stew", though it is unknown what it is made from or where the ingredients come from.
- Information on the location of each prisoner is highly restricted and only accessible to Prison Staff. Even senior Ghoul Investigators cannot access this information.
- The name Cochlea is a reference to the primary organ of hearing in the human ear of the same name. The cochlea is coiled like a funnel from wide on top and narrowing downward in levels to process sound.