Fort Imai is a fortified Mongol encampment in Umugi Prefecture. It is one of the three major Mongol Territories in Toyotama, so clearing it counts toward the region's liberation trophies.
Freeing Toyotama's territories lifts the fog of war across the region and reveals unfound locations. As a major territory, Fort Imai pays better than the small camps around it.
Izuhara
Izuhara is the southern region of Tsushima and the first one you explore in Act 1. It is where you rescue Lord Shimura from Castle Kaneda, meet most of your allies and learn the stealth tools that turn Jin into the Ghost.
Akashima Village
Akashima Village, in the prefecture of the same name, is the starting point of Norio's storyline. It has a full set of vendors, so it is a good resupply stop in western Toyotama.
Bamboo Forest Hot Spring
Bamboo Forest Hot Spring sits in Kushi, part of Toyotama, and is one of the game's 20 Hot Springs. Soak there once and Jin's maximum health goes up permanently.
Castle Shimura
Castle Shimura is the seat of Clan Shimura in Toyotama and the biggest battle of Act 2. Khotun Khan holds it after the invasion, and you retake it in The Fate of Tsushima alongside every ally you have gathered.