Yoshihiro Togashi, creator of the manga series Hunter x Hunter, seems to have a big interest in the continent of Africa. For example, the Dark Continent in the Hunter x Hunter series is clearly a reference to subsaharan Africa. Why? It is subsaharan Africa that was also called the Dark Continent. To the Europeans, Africa was and still is known as a mysterious place, especially up until before the 19th century. Welsh journalist and explorer, Henry M. Stanley was probably the first to use the term in his book "Through the Dark Continent" which was written in 1878.
The map above dates back to 1554. See how it resembles the type of map drawn by Togashi. Furthermore, one can say that "the Demon World" in his other manga series Yu Yu hakusho is another reference to Africa. Just food for thought.