It's a replacement for the default menpo mask in the game. This will give you a cool mask, which is the Glowing Oni mask. It's a little bit fiddlier than the default mask, and it doesn't have as many items, but it works much better for the current game. 

I've tried to make it as user-friendly as possible. You just need to be able to put it on your face, and it fits pretty well. It also doesn't make you look like a crazy person, and it's pretty easy to use.