The packing starts to nake sense once you consider the very high air humidity (90-95% saturation) of air in Japan & during the summer the air is both humid and

The packing starts to nake sense once you consider the very high air humidity (90-95% saturation) of air in Japan & during the summer the air is both humid and hot. Unless the bag is air tightly resealable or each piece is individually sealed, you need to consume the single bag of food at once as the rest will otherwise quickly go bad in the hot humid air.