Shukan Josei Prime, a weekly aimed at women, has an article on something very basic - but it's often interesting to look at the basics!
"Sake trivia: What to know before you drink, what's the difference between 'dry' and 'sweet'?" starts off with the usual line about sake having become so popular worldwide, and being part of the proud tradition of Japanese cuisine.
Then it switches to asking the reader if they really understand sake - for example, can they explain the difference between "dry" and "sweet"?
The first section covers different tastes in different regions, quoting Itō Zenshi, a researcher in the history of sake brewing who published the book "Edo Izakaya" in October 2017. He explains that nihonshu-do (日本酒度, also known as sake meter value) acts as a rough guide. Sake contains residual sugar left over from the brewing process, and sake with more sugar is sweet whereas sake with less sugar is dry. (There's no substance that makes sake dry.)
There are historical factors behind sake being served chilled (冷や, hiya, glossed in the article as 常温, room temperature) and warm. Back in the Edo period, sake was usually served warm - even in summer. There were exceptions, mainly religious - in Shinto ritual, sake offered to the gods or drunk at festivals was cold. It was only around 1975, when ginjō styles became popular, that chilling sake became the norm in order to enjoy its more delicate aromas. It could also have been influenced by the practice of chilling white wine.
It's also possible to tell regions by their preferences. Tōhoku likes it clean and light, while warmer regions prefer their sake full-bodied and sweet. When you look in detail, however, some areas go against the local trend. Aomori and Fukushima in Tōhoku produce sweeter styles, while Nangoku Tosa (Kōchi Prefecture in Shikoku in the south) goes for dry. Itō picks out local dishes as having a decisive influence on local sake.
The reporter also asked a brewery owner for her take. At the tender age of 27, Kita Mayuko is in line to become the 9th owner of the Kita brewery, founded in the late Edo period in Shimane Prefecture. She has been working in the brewery for three years. She starts by clearing up some terms that she find are often confused: the kuramoto (蔵元) is the owner of the brewery, while the tōji (杜氏, often termed "master brewer") is the one with ultimate responsibility for the brewing. They used to always be different people, but recently some brewery owners are also the master brewer. Historically, tōji would spend the brewing season working away from home in someone else's brewery, and the rest of the year at home growing rice or fishing. These days, they're increasingly likely to be permanent employees who spend all year at the brewery.
Kita also let the interviewer in on how the same rice and water can produce different flavours. One factor is the yeast - there's a choice between yeasts that produce aroma, and ones that produce acidity. The end result will be completely different. Another way to make the same ingredients into different sake is nihonshu-do, or making the sake sweet or dry. This requires controlling the specific gravity of the liquid to leave some sugar. She comments that young people these days tend to like lighter flavours.
The interviewer was surprised to hear that brewery staff work completely under their own initiative. Kita explains that everyone working on their signature Kirakuchō (喜楽長) sake abstains from eating nattō (fermented soybeans) during the brewing period. The microbes in nattō are particularly fierce and can contaminate a batch of sake, causing the fermentation to go bad. Brewing staff also take special care of their health so they're not taken out by colds over the winter brewing period.