To My Love is a written record from Ghost of Tsushima's Records set, left by locals during the Mongol invasion. You find it at Komoda Town in Izuhara, and it counts toward the Avid Reader trophy.
Go to Komoda Town in Izuhara and look for the paper or scroll to read. Komoda Town is a settlement, so you can usually walk in and look around once the area is safe.
Also at Komoda Town: the Komoda Bamboo Strike.
Komoda Bamboo Strike
The Komoda Bamboo Strike is a sword-timing challenge in Komoda Town in Izuhara. Cut through all the bamboo with the right buttons and it counts toward raising your maximum Resolve.
Aaruul
Aaruul is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at a camp south of Izuhara Clearing in Izuhara, and finding 20 artifacts counts toward the Know Your Enemy trophy.
Adachi Dragon Mask
Adachi Dragon Mask is a New Game+ mask sold by Baku the Voiceless for 5 Ghost flowers. It does not exist in a first playthrough.
Adak Tree
Adak Tree is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at Yoichi's Crossroads in Izuhara, and finding 20 artifacts counts toward the Know Your Enemy trophy.