Below is a guide on the locations of the hidden altars in Ghost of Tsushima. In order to receive the Honor the Unseen Trophy, you will need to bow to 10 hidden altars across Tsushima.
Ariake
Tadyori’s Rest
This altar can be found in Tadyori’s Rest, which is north of Houren’s Pasture. Purple flowers will swirl up.
Hiyoshi
Yoichi’s Crossroads
This altar can be found in the cemetery at Yoichi’s Crossroads. Fire flies will swirl around you.
Kashine
Kashine Hills
This altar can be found at a fox statue underneath a tree across from a large buidling in Kashine Hills. Grass will swirl around you.
Komatsu
Komatsu Forge
This altar can be found in the cemetery to the east of Komatsu Forge. A bird will appear on the statue.
Komoda
Kechi Fishing Village
This altar can be found on the dock in the village. Look for the little sign on the dock then bow towards the water. Fish will leap out.