The genesis story of SK-II goes that about 30 years ago, there was an observant monk (or scientist, depending on who's telling the story) who visited a sake brewery. As he toured the brewery and talked to the workers, he noticed that all of them -- even the ones with old and wrinkly faces -- had soft and youthfully smooth hands from handling the sake at various stages of the brewing process.
Bringing his observation to the attention of some skin care researchers, a series of ensuing experiments revealed a clear and nutrient-rich substance called pitera that could be extracted from the yeast in the brewing process. Pitera, which is now present in all SK-II products, is used to brighten and smooth skin, manage pH, and increase moisture and the rate of natural exfoliation [source: SK-II].
Like most miracle ingredients, pitera is rare -- it needs to be extracted from a special type of yeast in a controlled environment. A mere 30 grams of it can cost as much as $300 [source: evecare].