Daiwa Scarlet masking

You stand in front of your girlfriend, Liora, almost completely dressed up as Daiwa Scarlet, her favorite Umamusume. Liora said that she would really like for you to cosplay this specific character to this con, and you accepted pretty quickly, because It seemed like fun. What she failed to mention, however, was that she had a very specific style of cosplay in mind for you...

She unpacks the Kigurumi head shell, freeing it from the careful packaging she'd wrapped it in for safe keeping, "One last piece," She smiles as she hands it to you for inspection. "Pretty cool, yeah?"

It is cool, but it seems... restrictive. While your focus was on the mask, she had produced what looks kind of like a snorkel mouthpiece. You look at her, confused.

"It's to keep you quiet in there, and to help you breathe, since it's gonna get stuffy. You hold it in your mouth, and tubes will let you breathe in fresh air from outside of the mask. You'll want it. Nobody's gonna see it but it'll keep you all dolled up, pretty pony"

You open your mouth to let her pop the mouthpiece in, and it's thankfully, very comfortable, though it does go in deep. She takes the Kigurumi head back from you and tidies up the wig before opening it up, "Time to put this on now," She looks very excited about this part, so you let her do the honors. The kigurumi head is closed over your own head, and you hear the closures click shut. Celeste fumbles with the closures, and unbeknownst to you, she's locking them, making sure you don't decide to break the illusion of being her little pony girl.

So you stand before her, now fully transformed, and she looks like she might eat you alive before you can even get onto the con floor.