Sadao used to run Kuta Farmstead as headman and is one of the Adachi conspirators. He was removed after hoarding rice and having protesters killed. He hides at Ariake Lighthouse while Masako and Jin work their way to him through his family.
You follow his brother Hachi's cart and take Hina in for questioning. A map of Hachi's routes and a tip from Junshin lead to the lighthouse. Clear the bandits below before climbing up.
At the top he says Masako killed his wife and brother and says she should have died with her family. Masako kills him.
Masako Adachi
Lady Masako Adachi is the only survivor of Clan Adachi and one of Jin's allies. Her husband and sons die in the Mongol landing and the rest of her family is murdered the same night. Her side storyline, Masako's Tales, has you hunting the people behind that massacre.
Hachi
Hachi is Sadao's brother and runs supply carts between camps. In The Headman, Jin and Masako follow his cart to find Sadao, and in The Husband he tries to free Sadao's wife Hina.
Hina
Hina is Sadao's wife. Masako and Jin take her to the Adachi Estate for questioning in The Husband. She is scared of Masako and much more willing to talk to Jin.
Junshin
Junshin is a kind monk who turns the Golden Temple into a refuge and runs survivor camps across Ariake. He is the man Jin and Masako keep going to for leads in Masako's Tales, though he worries about her thirst for revenge.