@VerticalVectors
I think it's just an accessory worn over the shirt. I'm way more confused by what looks like a maid uniform that is below the piece you pointed out. The way it is drawn it looks like there's an invisible body inside of it, because that dress sure doesn't look like it's laying flat on the ground.
hehe talking about fictional wardrobes yaaay 👀✨
ur right on it probably being a layering piece
but off the mark about that dress below
not a maid uniform - simply a very classic high collared shirt layered over a sleeveless pinafore/dress
(admittedly can look apron like but its enough of its own aesthetic that it stands separate of the "maid" look)
and from what i see, the fabric of both the dress and shirt seem to be naturally flouncy
on top of that, the vertical seams/pleats can add volume both between and along the pleats, even when flopped on the ground
does look a bit body like tho ngl
but those are ur fun facts of the day 😎👍🏼
signed, ur neighborhood manga-reading-forum-using clothing appreciator 😌✨