What is shochu?

Japanese law divides shochu in two, and the division is about the still rather than the ingredient. It is the single most useful thing to understand about the category, because the two halves are barely the same drink.

Korui shochu is distilled in a continuous column still, which strips out congeners and produces something close to neutral. The law caps it below 36 percent alcohol. It's made industrially, it's cheap and it belongs to no region. It's also the base of most canned chuhai and most izakaya highballs in Japan. Nothing is wrong with it; it is simply designed to taste of very little so that whatever you mix into it can taste of something.

Honkaku shochu is the other half, and it is not a separate legal class. It is a label, and what earns it is narrower than most English writing says. Article 3 item 10 of the Liquor Tax Act lists six permitted mashes for single-distilled shochu, lettered i to he. A bottle can be labelled honkaku if it falls under the first five. Grain or potato with their own koji, grain koji alone, sake lees, sugar with rice koji, or one of those with a short list of permitted additions. The sixth is the catch-all, and it is the one that may have sugar and other things added after the still. Honkaku, meaning authentic, is the label rule’s way of saying this bottle came off the named list rather than out of the everything-else clause.

In practice, read the label rather than the packaging. Both classes must name themselves, and both come in glass, in cartons and in plastic, so the container tells you nothing. A korui bottle says renzokushiki joryu shochu or shochu korui. A single-distilled one says tanshiki joryu shochu or shochu otsurui, and adds honkaku if it qualifies. The one word that settles nothing is white liquor: the National Tax Agency lists it as a permitted alternative name for both classes, so a bottle carrying it may have come off either still. Both are on this site, and the tool will tell you which you are holding.

Three koji moulds are used in Japan, they are commonly called yellow, white and black, and the difference between them is not decoration. It is acid.

Black koji is Aspergillus luchuensis. White koji is Aspergillus luchuensis mut. kawachii, an albino mutant of the black one found in the early twentieth century. That's why the two behave so similarly. Both throw off large amounts of citric acid, which drops the pH of the fermenting mash far enough that spoilage organisms cannot take hold.

That is the whole reason shochu is a southern drink. Kyushu and Okinawa are hot. Fermentation in a warm room is a race between your yeast and everything else in the air, and a mould that acidifies its own mash wins it. Yellow koji, Aspergillus oryzae, the mould used for sake and soy sauce, produces very little citric acid and was historically unreliable this far south.

What you taste: black koji tends to give a heavier, richer, more savoury spirit with a sharper finish; white gives a cleaner, softer, sweeter one. Yellow koji, now usable year-round because refrigeration solved the problem it could not solve for itself, gives something fruity and closer to ginjo sake. Nishi Shuzo built a whole reputation on that last one. Their Tomino Hozan is a yellow koji sweet potato shochu, and it overturned the assumption that imo shochu had to smell of the field.

Awamori sits inside the same legal class as honkaku shochu, and it is a different drink with an older history. It has been made in Okinawa since roughly the fifteenth century, when distilling reached the Ryukyu kingdom through its trade with Siam. Mainland shochu most likely descends from it rather than the other way round.

Two things are requirements and one is a habit, and almost everything written in English gets that split wrong. The koji must be black koji, and the mash must be all koji, zen koji shikomi. Those are written into both the label rule and the Ryukyu origin standard. The long-grain Thai indica rice is not: the word for Thai rice appears nowhere in either instrument, and no origin rule applies to the rice at all. It's what nearly every distillery uses, because of how it behaves under all-koji fermentation. They could stop tomorrow and the bottle would still be awamori.

That last point is the one worth slowing down on. A shochu mash is built in two stages. First a mash of koji and yeast. Then a second, where the bulk raw material goes into the working ferment: the potato, or the barley. Awamori has no second stage. Everything is koji rice, fermented in one go. It is why awamori is denser, more savoury, and why it ages so well.

What the name legally turns on is narrower than the geography suggests. The rule permitting a bottle to say awamori asks for rice koji made with black koji mould, water, a pot still and nothing added afterwards. It says nothing about Okinawa. The island comes from a separate instrument, the Ryukyu geographical indication. Worth keeping the two apart in your head.

Awamori aged three years or more is kusu. The traditional method is shitsugi, topping up older clay pots from younger ones down a chain. Same principle as a sherry solera.

Japan protects five shochu and awamori origin names as geographical indications. The National Tax Agency administers them. The power to do it isn't in the Liquor Tax Act, where English writing almost always puts it. It's in the Act on Securing of Liquor Tax and on Liquor Business Associations, article 86-6. These are not marketing terms. A producer outside the named area may not use the name, however similar their spirit is, and each name carries a production rule stricter than the shochu definition itself.

Iki, Kuma and Ryukyu were designated in 1995, under the system Japan built to meet its WTO TRIPS obligations. No individual name is registered with the WTO, because TRIPS keeps no register of spirit names. It obliged member states to protect origin names, and this system is Japan’s answer to that. Satsuma followed in 2005. Tokyo Shimazake was designated in March 2024, the first new one in eighteen years. Most English-language writing on shochu hasn't caught up with it yet.

The label won't usually tell you. It's the single biggest reason two bottles of the same raw material end up in different worlds. A pot still can be run at ordinary air pressure or under vacuum, and both are honkaku shochu. Neither the definition nor any of the protected origin names says a word about pressure. The Satsuma and Ryukyu standards ask for a single distillation in a pot still and stop there.

Lower the pressure and the wash boils cooler. Distilling the same mash from 16 percent down to 1, the pot sits between 89 and 99 degrees at ordinary pressure and between 43 and 51 under vacuum. That is a gap of roughly fifty degrees held across the whole run, and it changes what ends up in the glass in two separate ways. Heat makes compounds a cool still never forms at all. The heavier aromatic molecules, the ones carrying earth and roast, need that heat to come over. Under vacuum they stay behind in the pot.

What comes out is not a cleaner version of the same spirit. Atmospheric distillation gives the roasted, oily, unmistakably-sweet-potato style. Vacuum gives something lighter and more fruity, often read as apple or banana. It's a different drink made from the same mash. That's why the choice belongs to the distiller, not to the recipe.

Two things worth knowing before treating vacuum as the modern improvement. The fusel alcohols people assume it strips out come across essentially unchanged. And with fewer heavy compounds in the spirit, ageing has less to work on, and trace off-notes that heat would have masked have nowhere to hide.

In practice the split runs by raw material. Sweet potato and black sugar are predominantly atmospheric, barley predominantly vacuum, rice does both. If a barley shochu tastes surprisingly like nothing much, that is usually the still and not the barley.

They are different drinks, and the confusion is mostly an American licensing artefact rather than a genuine ambiguity.

Korean soju is defined by its method rather than by a single ingredient. Strength isn't the line between it and shochu either: soju is sold from the mid teens to over forty percent. The overwhelming majority of what is sold is made by diluting highly rectified ethanol, distilled from tapioca, corn or molasses in a column still, then sweetened and flavoured. Traditional soju uses nuruk, a wild-inoculated cake of ground grain, rather than koji cultivated from a single strain.

Honkaku shochu cannot be made that way. It is single-distilled in a pot still from a defined list of raw materials, with koji, and nothing but water may be added afterwards.

Now the licensing part. This is where it matters if you're holding a bottle. In many US states a beer and wine licence cannot sell spirits. Since the 1990s there's been an exception for soju at or below 24 percent. There was no equivalent for shochu. So Japanese shochu that wanted to be sold by restaurants with beer and wine licences was labelled soju.

That has now been fixed in the two states that matter most. New York amended its law in July 2022. California signed AB 416 on 10 October 2023. Both let shochu at or below 24 percent be sold under a beer and wine licence, and under its own name. Bottles printed before those dates are still in circulation, so a bottle in your hand labelled soju may well be shochu.