Gate
A Gate is a passageway between worlds, typically established by summoning.
Transience
Gates are normally temporary, only existing during the act of summoning, and probably also for desummoning. However, 23 permanent Gates exist within Tokyo.
Details
Each Gate corresponds to a specific region of the game's version of Tokyo. This might imply that the 23 Gates located in other worlds and the 23 Gates in Tokyo are one and the same. But if so this is a scraped detail as, according to chapter 7 of the main story, each Gate in Tokyo can connect to multiple other world gates, albeit with varying affinities.
Some gates have two different names, one appears in scenarios and one appears in data. Given the fact the data haven't been used for anything in game, it's possible that those names are outdated/prototypes.
Takamagahara
Region: Chiyoda ward (千代田区)
Representative:
Land of Wa
Region: Chuuou ward (中央区)
Kamuy Kotan
Region: Minato ward (港区)
Representative: 
Korpokkur
Hourai
Region: Shinjuku ward (新宿区)
Midearth
Region: Bunkyou ward (文京区)
Prototype name: Sin
Deva Loka
Region: Taito ward (台東区)
Prototype name: Veda
Nirai Kanai
Region: Sumida ward (墨田区)
Oceanic Realm
Region: Koto ward (江東区)
Xanadu
Region: Shinagawa ward (品川区)
Shangri La
Region: Meguro ward (目黒区)
Prototype name: Agartha
Yggdrasil
Region: Ota ward (大田区)
Prototype name: Valhalla
Representative: 
Surtr
Kitezh
Region: Setagaya ward (世田谷区)
Prototype name: Rus' Khaganate
Representative:
Tír na nÓg
Region: Shibuya ward (渋谷区)
Eden
Region: Nakano ward (中野区)
Representative:
Gehenna
Region: Suginami ward (杉並区)
Olympus
Region: Toshima ward (豊島区)
Prototype name: Elysium
Babilim
Region: Kita ward (北区)
Great Spirit
Region: Arakawa ward (荒川区)
El Dorado
Region: Itabashi ward (板橋区)
Aaru
Region: Nerima ward (練馬区)
Old Ones
Region: Adachi ward (足立区)
Representative: 
Azathoth
Agisymba
Region: Katsushika ward (葛飾区)
Utopia
Region: Edogawa ward (江戸川区)
Prototype name: Atlantis
