A Steward Construct west of the Dueling Peaks provides a clue about using keys of water to reveal a shrine.

Quest Location

At 0931, -1902, 0030 (west of the Dueling Peaks mountains), enter the east side of the stone structure and talk to the Steward Construct to start the quest.

How to Complete the Quest

There is a shelf nearby that has a Frost Emitter, and there is also a Frost Emitter to the northeast, next to the river. Activate one of the Frost Emitters and use it to make three squares of ice. Bring each square of ice to the stone slabs next to the Steward Construct. Rotate it to be a diamond shape, like the diamonds on the stone slabs. Then push each square of ice onto the diamond shape in each slab. If it is too large, you can throw a fire fruit at the campfire, then hold the ice diamond near the fire to make it smaller. When you have put an ice diamond into all three stone slabs, Jochisiu Shrine will appear.