Four is an unlucky number here in Japan so you very rarely see things sold in sets of four. This isn't usually a problem until you're buying things that come in twos, for example pocket warmers made especially for shoes. They sell them in packs of five so either one of your feet has to go cold or you are forced to buy two packs. It's kinda like the hot dog, hot dog bun mystery in America and just as annoying. What's more annoying is that I need pocket warmers for my feet in the first place since they don't heat the classrooms and apparently don't believe in insulation. Am already prayng for spring.