This is a Side Tale in the Iki Island Expansion for Ghost of Tsushima: Director’s Cut. These are completely optional but if you’re aiming for all Trophies, must be completed towards that goal.
Investigate the battle site
To begin this Tale, make your way to Lake Nagata where Jin will hear some crying in the distance. Head into the nearby raided survivor’s camp and speak to a man there to learn that a monk was responsible for the raiders not losing their lives at the hands of the Eagle Tribe. Head up the slope after and you’ll find a woman, Hotoke, who you should speak to.
Hotoke will agree to show you where you can find the rescue party so follow her and she’ll eventually lead you to the battleground at Kidafure and the body of her one of the villagers part of the search party. Follow this trail of bodies and you’ll find some rice knocked over and some footprints you can follow.
Eventually, the trail leads to a group of Mongols, you can either sneak up and use a Chain Assassination or a Stand-Off as there are only these two Mongols for now. Once defeated, survey the beach ahead and examine all the points of interest, you’ll learn that both the monk and Hotoke’s husband are on different sides of the beach, ready to be executed.
Choose which hostage to save
You have to make a choice at this point, there is no way to save both, regardless of how careful you are. If you’ve been listening to Hotoke throughout this Tale, you can discern that it would be hard for her to live without her husband but your choice won’t matter too much so feel free to choose whatever hostage you like.
Once you’ve made your decision, head toward that hostage and prepare an Explosive Arrow to deal with the Shaman and then quickly dash over to said hostage, preventing the Mongols from killing him. Kunai works well here as it’ll buy you the necessary time to dispatch the nearby Mongols. Once you’ve defeated them all, release your chosen hostage and Hotoke will react to your choice, bringing this Tale to an end.