What is a Satsuma Imo?

Hello, or should I say oyattosaa, from the home of the Satsuma imo – warm and humid Kagoshima, Japan. For regular readers of Kanpai you might have noticed that a lot of the shochu that have been reviewed, especially imo (sweet potato) brands, are produced in Kagoshima. The particularly curious among you may have looked it up only to discover that Kagoshima is the southernmost of the mainland prefectures, located on the south end of Kyushu Island, and about as far as you can get from Tokyo without being in Okinawa. How did this remote place become so central in the shochu world? Good question. Shochu has a history of about 500 years, so let’s start … in the middle.

How a South American tuber became a staple crop in Japan

In 1705, a sailor named Riemon (利右衛門) returned from a voyage to Ryukyu Kingdom (now Okinawa Prefecture) with a strange, potato-like food. In those days of feudal Japan, present-day Kagoshima was known as the Satsuma Domain (薩摩藩), and it was ruled by the Shimadzu Clan (島津氏). The Ryukyu Kingdom was technically an independent country, though by this time the Ryukyuan king paid tribute to the Shimadzu Clan and the Shogun in Edo (modern Tokyo). Up until this time, Satsuma had often struggled through poor rice harvests due to its climate, geography, volcanic soil, and numerous typhoons. This new crop, which we know as the sweet potato, grew well in these conditions, and it flourished around the port town of Yamakawa where Riemon first planted his seedlings.

The locals called it kara-imo (唐芋, カライモ), or literally “potato from China”, as kara was the term used to refer to China and other foreign countries at the time (also used in kara-age, fried chicken). Native to the tropical regions of the Americas, and having been introduced to the Philippines by Spanish colonists, sweet potatoes had spread to China’s Fujian province and then the Ryukyu Kingdom by the early 1600s. Although Riemon had brought the sweet potato seedlings to Satsuma from Ryukyu, they were referred to as “Chinese potatoes”, perhaps because that’s what the Ryukyuans had called them.

Due to the plentiful sweet potato harvest, the Yamakawa area was able to avoid a crop failure that affected Kyushu Island in the 1730s. The success of this crop became known to the wider Satsuma Domain, and eventually the central government in Edo (Tokyo). One of the men responsible for popularizing it, the agronomist Aoki Kunyo, referred to it as Satsuma imo (薩摩芋, さつまいも), literally “potato from Satsuma.” To this day, the most common Japanese term for sweet potato remains Satsuma imo and Kagoshima Prefecture has endured as Japan’s top producer. To compare, the regular brown-skinned tuber that we refer to as a potato is called jaga-imo (じゃがいも). As with kara, the jaga in jaga-imo refers to a corrupt pronunciation of Jakarta, where these potatoes came from as far as anyone in Japan knew at the time.

Riemon, the sailor who brought sweet potatoes to Satsuma, did not have a last name since he was not from the samurai class. However, he was later given the name Maeda Riemon (前田利右衛門) and upon his death was deified. He was then enshrined at Tokko Shrine (徳光神社) in Yamakawa. The shrine is informally called Kara-imo Shrine. Riemon’s name also lives on in a line of shochu produced by Ibusuki Shuzo, based in Ibusuki City, the municipality which encompasses current-day Yamakawa town. Ibusuki Shuzo also produces a shochu named after the Satsuma Domain: Satsuma-Han (薩摩藩).

As much as the satsuma imo became an important agricultural product for Satsuma during the 1700s, at the time the staple crop was still rice. In Japan’s feudal system, rice was king. Each feudal domain was assessed based on the amount of rice they produced, measured in koku (石), approximately the amount of rice it takes to feed one person per year. One koku is 10 to (斗), which is in turn 10 sho (升). One sho is the equivalent of 10 go (合), and one go is 180 ml. These measurements are still seen in modern Japanese today, including sizes of bottles of sake and shochu, and to note the volume of rice cookers.

At its peak, the Satsuma Domain produced 770,000 koku of rice, which was the second-largest of all the domains in Japan. This meant, however, that rice was incredibly valuable. Making alcohol, whether sake or shochu, required copious amounts of rice, which made it a luxury indeed. Eventually, someone realized that instead of using expensive rice to make alcohol, why not use cheap, plentiful Satsuma-imo?

Modern Usage of Satsuma Imo

Here in present-day Kagoshima, while the term Satsuma imo will leave no one unclear as to its meaning, and there are still some uses of the original kara-imo, most locals simply use the term imo (which would likely get you a jaga-imo, anywhere else in Japan). Thus, imo shochu always means sweet potato shochu, whereas jaga-imo shochu (an uncommon style) must be specified to get potato shochu. Yaki-imo, literally “roasted potato,” is always a roasted sweet potato. However, the katakana word “sweet potato” (sui-to poteto, スイートポテト), actually refers to a mashed sweet potato baked dessert. Delicious, but an unexpected surprise when first making that mistake.

Two other words sometimes used for sweet potatoes in Japan are kansho (甘藷), which you will sometimes see on shochu labels, and maruju (丸十), which is used almost exclusively in kaiseki restaurant menus to denote sweet potato. Maruju is a reference to the Shimadzu Clan’s family crest, which is a cross inside a circle. Even today this mark commonly decorates Satsuma Shochu. And that is your clue for my next topic.

Kanpai!