Priest, Monk
A religious leader wearing a mask could be either a monk or a priest. You don’t know, their face is covered by a mask!
Picture this leader in their mask. Listen to them chant prayers that reverberate throughout the building.
そう
None
None
This monk or priest is wearing a mask to protect their soul (そう). You aren't a monk or a priest, so they don't want your not-religious-enough eyes to dirty their soul.
Imagine the monk/priest's bright, pure soul shining behind the mask. You'll never actually see it, unless you're becoming a monk/priest yourself, and then your soul will need protecting too.