Head inside the cave where you encounter the Spider yokai. Head out the cave and go down the courtyard. Go right towards a destroyed house that’s burning and go around the back to check the backside of it. There are some planks and debris that you can use to reach the top of it where you’ll find the first Kodama.
When you exit the cave where you encounter the Spider yokai, go straight and go up the path that’s on the left where you’ll encounter an armored dog and a Yoki at the top of the path that will push a barrel down to try and kill you. After killing the enemies, about midway up the path, there’s a destroyed house on the left side. Walk up to it and check the corner, you’ll find the second Kodama hiding in the grass.
For the third Kodama, head inside the cave where you’ll first encounter the rat yokai, Tesso and climb the ladder at the end of the path of the cave. You’ll find the Kodama at the left side of the ladder. To find the Tesso infested cave, head to the first cave near the starting area where you encounter the Spider yokai and exit to the courtyard. Head up the path where you’ll encounter a Yoki and armored dog then past the three soldiers, the entrance is just on the left side where the three soldiers were encountered.
From the second shrine, go up the incline, climb down the ladder and head to the cave entrance on the left. Go right towards the dirty water and climb up the ladder. There’s a corridor that leads to another ladder where you’ll find a room that has a roaming Tesso. The Kodama is in the room beside the wooden cave door on the left.
To find the fifth Kodama, head to the basement of the castle where the Waira was guarding earlier. The entrance is near the cave entrance on the left where you find the fourth Kodama. Go straight and you’ll find a corner in between the ladder and stairs. The fifth Kodama is behind some wooden barrels.
The sixth Kodama is on the second floor of the castle. You must pull the lever of both bridges for it to rotate. Once it’s aligned cross the red bridge, then on the purple bridge, you’ll see a small room on the left. Go inside and break the crates on the right side, the Kodama is behind it.
For the last Kodama, you must rotate the purple bridge and align it leading to the tower of the castle. Once that’s done, head back down the first floor and go to the room where the large spiders were. Go inside the room on the left where you’ll find a rotating panel. You’ll see a hole on the wooden floor which you can jump from to head in the secret room that has the hot spring.