The Umbrella Corporation Empire is the official successor to the East Asian Confederation in which that was an official successor to the Empire of Japan, is a nation on Earth.
For previous history, see Japan
While the Empire of Japan was held onto by Koishi Komeiji for so long, Kogasa slowly worked her way up the ranks to one day surpass her friend.
It wasn't until 2150 that Gensokyo was completely brought into the Outside World, and when it did, it added more land to Japan.
By 2555 Koishi eventually got bored and decided to meet with the leaders of China, Korea, Cambodia, and India, to all merge together. They agreed, and so the Greater East Asia Treaty Organisation was dissolved, and the East Asian Confederation was established. Koishi decided to move the capital to Seoul as it makes more sense, since it was to be the soul of the Confederation.
In 2800 Kogasa Tatara formed the Tataranian Empire and tried to surprise her friend. Koishi was surprised, but, became too nervous and declined in merging. At this point did she start to worry a little about her friend.
Soon by 2805 Ma Ying-jeou was elected for Prime Minister after his long break from politics. Though soon by 2888 he had to step down, and soon Nue Houjuu became Prime Minister.
Later, in 2901, the East Asian Confederation was at war with Darth Vader, and along with Tataranian Empire and her allies, they were prepared to fight off the major threat and the last major war that the world has ever seen.
By 6501 the longest war was finally over and Koishi felt very exhausted and very beat. She could barely hold power for much longer. She accidentally fired the whole government cabinet in 6527 as she attempted to take hold.
It didn't last long though, as by 6530, the Tataranian Empire absorbed Canada, Serbia, and the Louisianan Empire, and it became the Umbrella Corporation Empire. By the end of that year, the East Asian Confederation was no more, and thus was absorbed into the Umbrella Corporation Empire.