The Nikkan Spa site has an intriguing theory about the popularity of Dassai, plus a look at developments in milling ratio.
The default assumption might be that Dassai's popularity is a result of outstanding aroma and flavour, but what if it was something else? Like the flash-in-the-pan fads that regularly crop up in fast fashion or (if you're in Japan) convenience store foods?
(There seems to be some kind of fried chicken war going on at the moment between Family Mart, Lawson and Seven-Eleven.)
These products don't necessarily sell because they're better, but because they're selling - everyone buys them because everyone's buying them. But does this apply to Dassai, a label that even those who know nothing about sake have heard of?
One of Dassai's most sought-after products is their junmai daiginjō migaki ni-wari san-bun (磨き二割三分, literally "polished to 23%"). The article quotes Goma Niikura, a food blogger and qualified sake expert, who explains that the more the rice is milled, measured by its weight relative to its unmilled state, the more time and effort is involved and so the more expensive it becomes. Almost nothing was milled to 23% when Dassai released this sake, so it attracted a lot of attention.
The same Dassai sake ended up in the limelight again when Japanese Prime Minister Shinzō Abe presented a bottle of it to Barack Obama during a state visit, and the brewery itself stood out for their refusal of traditional brewing technique, instead relying on automation and data analysis to create high-quality sake. All of these things made the company and the product popular, but have no relation to how the sake actually tastes.
These days there are a number of sake milled to 23%, and the milling ratio has been pushed much further - pretty much as far as it can go. The Tatenokawa brewery created Kōmyō (光明, meaning light or hope), a sake made from rice polished down to just 1% by weight of its original volume, which became almost impossible to get as soon as it was released despite a hefty JPY 18,000 price tag per 720 ml bottle. Considering that it's polished 50 times more than a standard junmai daiginjō, Niikura points out, you can see where the price comes from.
On the other end of the scale, and appealing to a different drinker, is Musuhi (むすひ) from the Terada Honke brewery. The milling ratio is 100%, meaning that the rice has not been milled at all. The reason why rice is milled in the first place is to create a specific flavour profile by eliminating the proteins and lipids found in the outer layers of the rice grain (particularly in sake-specific rice varieties where the starch is concentrated in the centre) so as you can imagine this would create a very different drink.
Conscious that the whole grain will be used, the brewery takes great care with their raw materials right from the start, with the condition of the rice fields, and stay close to traditional methods including using the yamahai method to start fermentation. They grow some of their rice themselves, with the rest supplied under direct contract, and are dedicated to organic farming and using natural methods of pest and weed control - such as ducks!
So while 23% used to be cool, now you can try both ends of the scale - from 1% to 100% - and everything in between.