In the coming cold season. I found a product called "2WAY Mask Case" at the 100-yen shop CAN DO and bought it.
Cute design with English printed
As the name suggests, it is a case for carrying a mask. There is an "open pocket" on one side to hold the mask in use, and a "spare holder" on the other side to hold a spare mask. Because it is simple, it is convenient even if you put two masks in it without being bulky in the bag. The mask in the open pocket may pop out, so it is safe to put the mask case itself in a clear file.
Clean and compact even after putting on the mask
The approximate size is 190 x 115 mm and the price is 108 yen (tax included). There are several designs, so why not choose one with fun?