The Arcana is the world Suikana come from and sometimes live in. It is not uncommon for Suikana to travel to other worlds, but they will generally return to the Arcana to trade or to interact with others of their kind.
There are a wide varieties of areas in the Arcana, although there are mostly untamed wilds outside of major cities. The explorable areas are part of these untamed wilds, and contain a wide variety of creatures. Hunting these creatures is a well-known source of goods, as is simply looking around for places someone may have abandoned items when they overestimated their skill.