The bento bag is a small cloth bag that allows you to store your bento in better conditions and also to have small improvised straps to hold bentos or more conventional and traditional lunch boxes. The particularity of the bento bag's fabric lies in the simple but elementary folding of the bag because to be able to create handles with a simple fabric you need a minimum of dexterity. You can also put away your bento accessories such as cutlery, chopsticks, and your water bottle, which can be very useful.
History of the bento bag
The bento bag in ancient Japan was a kind of tablecloth with traditional Japanese ornaments and patterns that could be found on many Japanese kimonos. It is said that the remnants of dress were used for this purpose before, to avoid making a mess. The so-called Furoshiki technique consists in folding a simple cloth to make a bento bag to take away: it is a Japanese folding and knotting technique which is not necessarily used only for the bento bag but for any other use of household tasks like a clothes wrapping or a gift. The word explicitly meaning furo meaning something and shiki meaning flat package.
We find its existing in Japan since the Nara era where it was used to protect precious or valuable objects.
So this bento bag will also be used as an accessory so that your sauces won't sink since it allows you to hold the bento with a stability and a center of gravity.