The Walls of Yarikawa is a main story mission under Jin’s Journey in Ghost of Tsushima.
Your task is to follow Yuna and Taka, and try to convince Yarikawa to join as an ally.
Here’s a walkthrough of The Walls of Yarikawa in Ghost of Tsushima.
Reward: Major Legend Increase.
To begin the quest, talk to Yuna at Yarikawa Stronghold.
Follow Yuna and Taka
Next, follow Yuna and Taka to the main area of Yarikawa.
Survey the area
As the Mongols surround Yarikawa, you need to survey the place first.
Get to the hidden entrance
Here, you have to get to the waterfall without alerting the Mongols. You should be able to sneak in easily through the burnt structures, as some Mongols are looking away.
Also, watch out for the patrols.
Head towards the stream.
Walk along the stream until you reach the waterfall entrance. Enter through the crack on the wall.
Follow the guard
Once you’re inside the stronghold, follow the guard.
Follow the guard to meet the steward.
The last objective is to talk to Taka at the swordsmith shop.