Costa Rica

Costa Rica (コスタリカ), officially known as the Republic of Costa Rica, is a nation in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west, and the Caribbean Sea to the east.

DRAGON Arc
Stephanie Gorgeouspalace's first job as a mercenary was in Costa Rica, where apparently a civil war was being waged. After her unit was eliminated, she was saved from death by Sunazara Chimitsu.

Necromancer Arc
Prior to Esther Rosenthal being invited to supervise Hishigata Mikihiko's research team, several mysterious objects including were taken from outside of the Academy City.

Trivia

 * In real life, Costa has only had known one civil war, the Costa Rican Civil War, a bloody 44-days civil war in 1948, after which the government abolished the military permanently. A second civil war would be extremely unlikely, but it is most likely a result of the Toaru universe being an alternate history.