The Akai Amulet
Traveling to and from Amaterasu is very difficult for most people living in Sekai. To travel there on foot an adventurer would have to brave a great jungle, only after a long trek though empty plains. It has become quite common for average folks to take a boat from Shiro to Amaterasu for safety reasons.
The capital is bustling, nonetheless, and has surprising popularity for a city so hard to reach on foot. Aside from the population of eastern Sekai, Amaterasu has many travelers from the other continents of Aka.