Japanese customers spend a lot of time each year changing their clothes for each season. Japan has four main seasons plus two extra ones (rainy season & the start of high humidity weather).
When changing season its customary to pack away clothes & prepare for the next season. To help when doing this a nifty product called bouchuuzai 防虫剤 or as we know in the west, mothball repellant is a useful product at these times of packing.
The Japanese version is small, light and has a time code built in which tells you when it has expired which is very convenient.
The ones featured below are a one year type. So you just wash your clothes, fold them up, place them into a plastic bag or box together with a bouchuuzai unit and the jobs done.