The Traitor is Masako Tale 4 of 9 and the last Act 1 part of her hunt, set in Ariake. You use a supply map and a monk's help to corner Sadao at a lighthouse. It rewards the Charm of Incineration, the Warrior's Bounty Dye Kit and 2 Silk.
Part 4 of 10 in Masako's Tales
Part 16 of 66 in Tales of Tsushima
Take the supply map from Hachi to Junshin at the Golden Temple. He set up the camp network and recognizes the routes. Ask him which marked spot does not belong to the camps, and he picks out Ariake Lighthouse. Head for the Ariake refugee camp to regroup with Masako, then ride to the coast, fight through Sadao's guards and climb the lighthouse.
Ride to the refugee camp in Ariake and talk to Masako. Head for Ariake Lighthouse. Kill Sadao's guards. Climb up to Masako at the top.
Masako reaches Sadao first. He taunts her that she should have died with the rest of her family, and she kills him on the spot. As with the monk in her first tale, her anger means the conspirator dies before he can give up anything useful.
The Headman
The Headman is Masako Tale 2 of 9, an Act 1 side tale in Ariake where you start hunting the first name on Masako's list. You trail a bandit-linked brother to find a former Adachi headman, and it pays a Charm of Resolve I and 2 Silk.
The Family Man
The Family Man is Masako Tale 6 of 9, an Act 2 side tale that starts at Omi Monastery in Kubara. You talk the monk Junshin into revealing where a former Adachi retainer lives, then go after him. It rewards the Charm of Ferocity and 2 Silk.
Image: Sucker Punch Productions / PlayStationThe Tale of Lady Masako
The Tale of Lady Masako is the Act 1 story tale where you recruit Masako Adachi after her clan is wiped out. It rewards the Samurai Clan Armor and is also Masako Tale 1 of 9, opening her side storyline.
The Husband
The Husband is Masako Tale 3 of 9, an Act 1 side tale at the Adachi Estate in Ariake. You try to get Sadao's wife Hina to talk, then track an assassin when things go wrong. It rewards the Charm of Dual Destruction I and 2 Silk.