Japan, or the Nation of Japan is a significant part of the Guilty Gear history. Because the Japanese' affinity to spiritual forces is seen as a threat, Justice made it her first target and it was destroyed in 2074. The destruction of Japan pushed the formation of the Sacred Order of Holy Knights.
Because of their spiritual culture, the Japanese have a natural ability to channel energy like Ki. This gives them enormous potential for combat and because of this, but they can be easily identified by Justice. After the destruction of Japan, very few Japanese are left. As a result, the United Nations placed them under colonies protected by magical barriers. The IPF is tasked to keep them inside colonies and those who escape are arrested or are listed under a wanted list.
Here are the known Japanese characters:
Note that Chipp Zanuff isn't Japanese even though he claims to be one. His love for the Japanese culture stems from his love for his master, Tsuyoshi. Crow is implied to be Japanese in Baiken's story mode.