Coffeeshop boy is the biggest idiot of all time.
Thanks for the translation. This is one of my favorites.
Washable kimono being a whole thing implies that many kimono can't be cleaned - Momo and her grandmother must be very careful eaters! I'd have soy sauce spots all over my kimono I think.
Traditionally Kimonos were silk which requires special care. Some kimono are from the late 1800s well before "colorfast" dyes were in use, or pre-shrunk cotton/wool were wide spread, and when you add in intricate and delicate patterns and in some cases embroidery, you can't just take a kimono down to the river with lye or toss it into a machine. It needs to be handled with delicate care. Hence the use of underclothes to keep sweat/oil from getting on the fabric.
So while a Kimono could be
cleaned it can't be "washed"