[The classical One Cup Ozeki stands in the middle. Gekkeikan's cup sake, also a large provider, is to the left. To the right is a new development, a Daiginjo.]
I made the acquaintance of sake via cup sake. There was a vending machine close to my first lodgings when I came to Japan in the early 1980s. The machine was wonderful: in summer it sold cold sake and in winter hot sake! In Holland, there were no vending machines selling either refrigerated or warmed products (I believe they still do not exist, although today people will cite environmental concerns for what is in principle a problem of both service and technical levels). I realized why the glass of cup sake was so thick: so that it would not break when falling down inside the vending machine on its way to the bottom where you could pick it up.
[The red one in the middle is a cup sake vending machine]
My local machine was also a gathering place for men from the neighborhood: they would come every afternoon at five and use the plastic crates stacked against the wall of the sake shop as stools. They would sit in a half circle around the sake machine and have a good time, without bothering others.
Of course, cup sake was not premium sake (but anyway, premium sake was still almost unheard of in the early eighties), but it tasted good all the same. When I was a student at Kyoto University and lived in a student home, I usually kept the glass cups of my One Cup Ozeki sake and recycled them as glasses for juice or cold tea. They were almost indestructible.
In the last ten years or so, cup sake has undergone an interesting transformation. In the first place, it has shared in he general quality improvement of sake. Even large makers as Ozeki now provide higher-priced cups with Honjozo or Junmai. Other makers are doing even better: Dewazakura from Yamagata and Maboroshi from Hiroshima are selling their ginjo sake in cups.
[Aluminum sake cans. Kikusui (Niigata), an unpasteurized, undiluted Honjozo, stands in the middle. A classical ginjo by Dewazakura from Yamagata is to the left. To the right is a ginjo by Seikyo (Hiroshima).]
A second thing is the use of steel or aluminum cans - the last two companies are examples. These are quite common now, but I prefer glass - it is more pleasant to drink from. Another development is that instead of cups we now also have mini-bottles, with about the same contents (180-200 ml.). They are no use when you are traveling, but they are a great way to taste many types of sake at home.
A third phenomenon, already going back further but still going strong, is the cup sake sold by makers of local sake (jizake). These cups with their colorful labels are usually only for sale in the areas where the breweries are located. So traveling around Japan and drinking as many different kinds of local cup sake has become a new sport (some people probably collect the cups or labels as well).
[Last but not least, also Daishichi makes an excellent cup sake - only available in Fukushima]
I found two Japanese guide books to cup sake, attesting to its popularity: The Cup Sake Best Selection 900 (yes, 900 different cups of sake from more than 500 breweries) and the even more interesting Local Cup Sake and Train Travel. To travel around Japan by train - buy a local bento at a small station - and a cup with the regional sake - that is indeed the best way to taste the regional sakes of Japan!