Located in Bamboo Grove in the map, make you way up to the main area with the statue in the center of the area.
To the right of the statue, you will see a small stone with yellow writing on it, head over and examine this to trigger a short cutscene with the clue for completing this puzzle in the cutscene.
After learning that "Hell" is the main part of the clue, make your way back to the central statue and interact with the figures until you find the one names "Hell".
Upon finding him, do a 180 spin so the Hell figure is directly behind you, and walk towards the rocks ahead of you. Keep walking to learn that the rocks are simply an illusion.
After walking through the false rock, use your Oni Vision to reveal the interaction to keep on advancing.