I bought this from MINISO Japan when I went for a trip a year or two back and have never used it.
the condition is just like it's brand new since it's never been worn. It can be adjusted from the back side.

PRICES CAN BE NEGOTIATED IF REASOBALE ENOUGH
(there are a few small white hairs on the cap as I have a cat, although I'll make sure to dust every single hair off)