The Sub-Cities (地下都市 "Underground City") are three subterranean cities in Mega Man Legends where the Prototype Anthro Units lived. While inside the Main Gate, Mega Man Volnutt uses a console to unlock the entrances to the Sub-Cities, which appear on the surface of Kattelox Island after a big tremor. Each Sub-City is protected by Reaverbots and contains one of the three keys needed to open the Main Gate's Central Gate, which has been automatically locked by Eden and required manual override through the use of the keys.
Sub-Cities
When Mega Man enters a Sub-City, the exit is locked and will only open when he defeats all Reaverbots in the area. Each Sub-City contains several abandoned buildings, and although located underground, the top looks like a starry night sky. The biggest building from each Sub-City contains a Central Gate key. Like the exit, this building's door will only open when all Reaverbots are defeated.
Sub-City 1
The entrance of Sub-City 1 (地下都市 エリア１ "Underground City Area 1") is hidden by the warehouse in the Old City. After finding the Bonne family inside the warehouse, the warehouse is destroyed in the battle between Mega Man and their Theodore Bruno, allowing Mega Man to find the Sub-City entrance. This Sub-City is protected by Karubuns, Arukoitans, and Orudakoitans. It contains the 'Watcher' Key.
Sub-City 2
The Sub-City 2 (地下都市 エリア2) entrance is located in Downtown and is protected by Karubuns and red Sharukurusus. It contains the 'Sleeper' Key.
Sub-City 3
The Sub-City 3 (地下都市 エリア3) entrance is located in Uptown and is protected by Gai-nee Tooren, a large Reaverbot that releases Red Horokkos and green Sharukurusus. It contains the 'Dreamer' Key.