I still have not become used to the quantities in which things are sold in Japan.
It is a little like the hot dog idiocy in Canada, where wieners come in packets of twelve and hot dog buns come in packs of eight. It takes a math whiz to figure out the number of packets of wieners required to arrive at a common denominator consistent with the number of buns in a package, dividing by the number of persons in your household and how many hot dogs you will have that will feed your family for x amount of days and then reconciling that with the best before dates of BOTH packages. (You might find it odd that the meat lasts longer than the bread). Perhaps it explains why some families eat so many hot dogs. If you were to make a slight error in your calculations or if you are unable to do math, you will end up with too many of one or the other and it is back to the store to get more of what you don't need, in which case you would end up with more of the other again. Its one of the those downward spirals.
In Japan things tend not to come in packets of four. And it would be a great social faux pas to give a gift in a quantity of four. Things often come in packs of three or five which can create strife and marital struggles for our family. The solution often involves knives.