I found a trivia in UCC coffee company website. It is that iced coffee was born in Meiji era in Japan, we have impression that every kind of coffee was originally born in Western countries though. So why was this made in Japan?
In Japan, they had custom to drink cold water because the water from well was clean, and it was popular that they kept something cold in river. So it might be a big reason that iced coffee became popular. On the other hand, in Western countries, it was regarded as non-sense or extravagant that they take trouble to make drinks cool except water, because it was dangerous that they drink something not to be heated which may cause food sanitation hazards.
I think it is great fact that Japanese iced coffee culture such as instant coffee and canned coffee spread in the world. And I thought it is very thoughtful that Japanese coffee shops make strong coffee beforehand in order to make it iced, so we can enjoy tasty iced coffee even after ice dissolve in the cup.
I found a video which an American man is trying to make Japanese iced coffee. So please check this out!