Kouran

Also known as Kōran, the invading empire from the west that has occupied one-third of the Nil Kamui. Kouran is known to be an ancient empire and a particularly greedy one at that. It's national colour seems to be green as seen with the soldiers under the command of Lady Koukaku that are dressed in a green military uniform.

Trivia

 * Kouran's real world equivalent is China, as is seen by the location (the west), it's description, the 'ancient, greedy empire' (the greedy might just be the Japanese opinion on China) and the names, Zhenhua is a Chinese name.