Heart of the Jito is a main story quest (Jin’s Journey) in Ghost of Tsushima.
Your task is to deliver a letter to Lord Shimura by sneaking into his room.
Here’s a walkthrough of Heart of the Jito in Ghost of Tsushima.
Speak with Yuna to begin the quest.
After the cutscene, follow her out of the temple and pick a new horse.
Enter Castle Shimura
Next, head towards Castle Shimura.
If you wish to save time from the journey, fast travel to Kubara Crossing.
You will see a waterfall there.
Swim towards the waterfall and there’s an area for you to climb up.
You’ll need your grappling hook as well.
Climb until you reach the wall. Squeeze through the hole.
Head to the bridge
Once you’re inside the walls, find your way to the stream / river. Not many guards will look down here.
Swim towards the broken bridge.
You’ll need to pass by some guards. Just stay underwater until you get past them.
At the bridge, you should be able to find a fallen log.
Cross the log.
Continue climbing up using your grappling hook. It’s the same route as the first time you poisoned the Mongols.
You will then reach the tower. Go through the tower and head to the garden.
Enter the keep
Unlike the first time, the ropes aren’t there for you to walk on.
Just go through the garden.
Sneak behind the guards.
At some parts, you just have to wait for them to leave and you can follow behind.
After the arch, you should see some tall grass.
On your left, there’s a platform for you to climb into the keep.
Once you’re inside, wait for the guards to move away.
Head to the top floor
The goal is to go to the top.
There’s a ladder here.
Climb up and you’ll see more guards. Go through the broken window and walk on the roof tiles.
Once you’re outside, you should be able to find another entrance into the building again.
You will then see Lord Shimura speaking with the samurai.
Get past them and head out of the building again through the first door you see.
Once you’re on the roof tiles, look for the ladder to climb up.
Keep climbing up until you reach the top part of the keep. There’ll be a guard here but you can easily avoid him.
Enter the building again and use the ladder to go down.
Leave the letter
You will then reach Shimura’s room. Place the letter on his table and you’re done.