The Okutama Mountains are a mountainous region on the western-most part of Tokyo, Japan. The mountain area was frequently used by the Kumakura Family, under Rohan Kumakura's leadership, to dispose of bodies connected to their organization, including Manaka Iwai. The area is also the location of the second murder in the Original Cyclops Serial Killings case.
In early November of 2001, Rohan Kumakura and his men took Manaka Iwai's body to the mountains. Thanks to the GPS transmitter Renju Okiura had given her, Renju and Hitomi were able to track her location, so they followed her into the mountains. As they hid and watched the Kumakuras bury Manaka's body, Rohan asked his men to stop, and removed her right eyeball.
After Manaka was buried and the Kumakuras left, Renju and Hitomi dug up her body. Renju convinced her to keep Manaka's murder a secret, fearing that the police would be unable to help and their lives would be in danger. He believed that neither So nor the Kumakuras realized that Manaka had given birth, and they would come after the baby if they ever found out. Togehter, Renju and Hitomi took Manaka's body to the Okiura Fishery Cold Storage Warehouse.
- The Okutama Mountains is the only location directly featured in AI: THE SOMNIUM FILES where Kaname Date and Aiba do not visit during their investigations, as well as the only location the player cannot investigate, even in flashbacks.
- The location's layout, however, is explorable in Hitomi's Somnium, PSYNCIN' IN THE MOUNTaiN.
- Within the game's assets, an image of the Okutama Mountains named ui_map_15.png (see top of the page) is included with other images used on the map screen when selecting a location to visit. Whether this is a placeholder image or an indicator that the player may have originally been able to investigate this location in-game is unclear.
- The real-life names of the 5 major mountains featured in Okutama are Mount Kumotori (雲取山, Kumotoriyama), Mount Mitō (三頭山, Mitōyama) Mount Ōdake (大岳山, Ōdakeyama), Mount Kawanori (川苔山, Kawanoriyama), and Mount Gozen (御前山, Gozenyama), among many others. It is unclear in which exact mountain Manaka Iwai is buried.
- Okutama, Tokyo on Wikipedia