Fumiki Inoue, president of Inoue Foods

Konjac cultivation continues since the Edo period

As its name suggests, konnyaku potato is the raw material for konnyaku, an indispensable ingredient in Japanese cuisine. However, it is a labor-intensive agricultural product, as it is difficult to find a suitable cultivation site, which requires a cool summer climate and good drainage, and it takes three years to harvest.
The domestic self-sufficiency rate is high at around 90%, but more than 90% of that is produced in Gunma Prefecture, and in Tokyo, production volume is very small, mainly in Hinode Village.
Konjac cultivation in Hinode Village is said to have begun in the mid-Edo period. Although new varieties now account for the majority of production, the native konjac from Hinode Village is also certified as an "Edo Tokyo vegetable."

Working in a konjac potato field on a slope. Senior citizens are being utilised.

Inoue Foods, the only konnyaku manufacturer in the village, is the driving force behind the continued production of konnyaku in Hinohara Village. We spoke to the company's representative, Fumiki Inoue, for more details.
"My father started making konnyaku in 1968. There weren't many jobs in Hinode Village that could provide cash income, so he wanted to create a job that I could do in the village. At the time, wood from the mountains was still selling well, so he sold one of his mountains and used it to build a factory."
At the time, konjac cultivation was thriving in Hinode Village, but there was no processing plant and the only processing was shipping the raw materials. The previous owner procured produce from the village and manufactured it, which apparently sold quite well amid the rapid economic growth and population increase.
Currently, in addition to producing our own produce with several producers in the village, we also purchase from outside Tokyo.

Konjac cultivation usually begins with purchasing seed potatoes. One-year-old seed potatoes, called kigo, are planted in the fields and cultivated, then dug up before frost and planted again the following year.
Konjac potatoes have a very bitter taste due to calcium oxalate, so they are not eaten by animals themselves. However, they are often dug up by wild boars and other animals, making electric fences essential to prevent animal damage.
The tubers harvested in the third year after planting are then processed to make konnyaku.
The crop is harvested all at once and then frozen for year-round production.

Planting konjac rootstock

The now rare "grasshopper kneading method" for making konnyaku

Most of the konnyaku currently on the market is made from konnyaku flour, which is made by slicing the tubers, drying them, and milling them into powder. Once milled into powder, it is easy to store and distribute, and also easy to shape. However, Inoue Foods has continued to insist on making raw konnyaku, which is made by simply grating boiled tubers.
"Using a method called 'Battam Kneading', we knead the grated konnyaku with a machine equipped with blades and then pour it into a molder. The texture changes depending on how we knead it at this stage. This machine is no longer being manufactured, so we have three long-standing machines that we are repairing and using."
The method, called batta-neri or butter-neri, is said to have been named after the flapping sound that occurs when the konnyaku is stirred. Although it is time-consuming, it has enduring popularity as the taste and texture are significantly different from powdered konnyaku.

Store frozen for year-round production

"My father's last words were, 'If the time comes when it is no longer possible to knead the batta paste, or when it is no longer possible to harvest konnyaku potatoes, then you should give up konnyaku production with dignity.' It's quite difficult, but I intend to do my best even if we are the only one left in Japan."
In fact, the number of konnyaku factories in Japan that still use the grasshopper kneading method has dwindled to just a few. It is hard work, such as cleaning the machines after each kneading, and even if some factories are considering adopting the method because of its good taste, it is difficult to continue.
However, when you actually try the finished "Sashimi Konnyaku (product name)" with soy sauce and wasabi, the unique chewy texture and flavor of the konnyaku potato spread throughout your mouth, creating a deliciousness that you can't find anywhere else.

The grasshopper kneading machine is no longer manufactured, but it has been in use for many years while being repaired.

Tokyo Metropolitan Agriculture, Forestry and Fisheries Foundation YouTube Channel

Unlike the production of flour, the process of kneading the konnyaku with grated raw potatoes creates countless air bubbles in the konnyaku. The amount of air bubbles is what creates the exquisite taste. The air bubbles also have the effect of improving the absorption of flavor when the konnyaku is simmered.

Initiatives to increase the number of "konnyaku lovers" on the observation floor

Another distinctive feature of Inoue Foods' factory is that it has a floor where visitors can observe the manufacturing process.
"There was an article about konnyaku from Hinode Village in a supplementary reader at elementary school, so there were many requests for tours. I loved field trips as a child, and when we rebuilt the factory in 1996, we built this floor so that people could see the manufacturing process. My wife was quite against it because it would cost a lot of money (laughs)."

There is an observation floor where you can get a full view of the manufacturing process.

As a result, it is now also used during business negotiations, allowing people to actually see the batta kneading method and understand its value.
Currently, domestic demand for konnyaku has been declining for the past 30 years, exacerbated by the COVID-19 pandemic, when convenience stores stopped selling oden.
On the other hand, demand for it overseas is increasing as a low-calorie, healthy food ingredient.
Konnyaku has been enjoyed as a convenient everyday food in Japan, but overseas it is treated as a special ingredient, such as being eaten in place of pasta in the form of konnyaku noodles, and has the potential to create new demand.

The "Konnyaku made in Tokyo" that Hinode Village and Inoue Foods have been working on may also see greater added value in the future.

"Sashimi Konnyaku (product name)" is popular for its unique texture and flavor.