Fort Yatate is a Mongol-held fort in Kashine Prefecture where Ryuzo's Straw Hats are kept. You sneak in during The Iron Hook to free them, and what you find inside changes how you see Ryuzo's men.
Jin infiltrates the fort to free the captured Straw Hats so they can help with the attack on Castle Kaneda.
The prisoners have not been tortured. The Mongols have been feeding them and treating them well.
Komatsu Forge
Komatsu Forge is a smithing town on the Komatsu and Tsutsu border where Taka builds Jin's grapple hook. You defend it in Hammer and Forge, which also frees it from the Mongols.
Adachi Estate
Adachi Estate is the abandoned home of Clan Adachi in Izuhara, where most of Lady Masako's family was murdered. You investigate it in The Tale of Lady Masako and come back during The Husband.
Aoi Village
Aoi Village is a village on the Tsutsu Plains that the Mongols occupy at the start of Act 2. Freeing it gives you the Key of Aoi, one of the keys for The Unbreakable Gosaku.
Arrow Peak Shrine
Arrow Peak Shrine is a Shinto shrine climb in Azamo, Izuhara, dedicated to Inari, kami of agriculture. Reach the summit to earn the Charm of Inari, a major charm: increases the supplies, predator hides, bamboo and yew wood you collect.