Increase
The dirt mask is a mask which, when put on, will greatly increase the amount of dirt.
Imagine putting it on, and suddenly the dirt around you increases by quite a bit.
ぞう
ふ, ま
None
Use the dirt mask to increase the dirt around you. The zombies (ぞう) are trying to escape, so you just keep increasing the dirt on top of them so they can't get out.
Zombie hands keep coming out of the ground, but as long as you wear the mask and increase the dirt on top of them, they won't be able to escape their earthly prison.