The locked gate behind the Fox Mask guy is called Shrine Vault Puzzle and you need a little walking to solve it.

Story Mode

1. From the locked gate look back and take the path to your left. (The path will be shown in the map)

2. Open the small door in front of you to start a short cinematic.

3. Examine the doll in front of you for the clues:

To extoll the advent of our clan, we bestow upon this sacred land the name "Heaven's Benediction."

Send forth to the sky a crane;
to the earth, a serpent;
and to the spring, a tortoise.

Pray for the prosperity of our clan.

4. After killing the monster (which will respawn after few seconds anyway) or hiding from it (which is the better option because if you get a little far from him he will never find you again unless you attack him), find one of the Crane, Serpent or Tortoise in your right and examine them for their icons.

5. Each time you find a correct one the whole wall of pictures will disappear and you need to find another wall of pictures in the area.

6. After finding all of them, now go back to the locked gate and open it using the clues.

• One of the clues you need to find has the middle piece of the lock, which means you can't just skip all of steps above.

Hard Mode

TBA

Lost in the Fog Mode

TBA