A Japanese girl at a (Japanese owned) private beach in Guam
I had first heard of the term of "3S" was from the Japanese (upper class) family social gatherings some 25 years back
Almost all of them were seasoned expatriates. Often the wives, while the usually quiet husbands unless attending corporate events, would exchange the fancy tidbits of their overseas' living and would eventually bring up the "3S" subjects. Many of these families had been stationed in several exotic countries already. Places like Paris, London, Madrid, New York,.. you name it. But those are all nothing but the steppingstones while they are climbing up the ranks (career ladders), also social status, toward the ultimate goals of transferring to one of the 3S cities. "Three best cities to live in the world."
You might have figured them out, too.
By the way, contrary to general public believe, especially to those Gaijin (Japanese slang for foreigners, Westerners in particular) who think they truly understand Japanese, none of these Japanese expatriates I know so far, neither all of my ethnic Japanese/Eurasian relatives (but for unknown reasons, at least, the 3S thinge is never mentioned), would want to stay in Japan, never ever.
There are three dream cities among the talented and successful alchemy in Japan, which consists of San Francisco, Sydney, and Singapore.
San Francisco, California, U.S.A.
The Economist Intelligence Unit's livability rankings for 2011 and July 2012 show Sydney had consistently placed in the top 10 most livable cities in the world, scoring well for having low pollution levels and abundant green space.