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2020, May, 15

10 days at a Koji maker
​Miyamoto Koji-ten


Engulfed by the great scent of steamed rice, the Miyamoto Koji-ten begins the day. (Koji-ten means a Koji shop) The pure white steam fills inside of the Koji room and overflows in the garden.


It's February 2020. I'm at the beginning of 10 days stay at Miyamoto Koji-ten in Nishihazu, Aichi Pref. I'm here for helping and learning about the work of a Koji maker.




Miyamoto Koji-ten

Miyamoto Koji-ten is a new and small, for now, Koji maker located close by the sea. Mr. Miyamoto runs everything by himself from producing Koji to replying to the orders from customers. (He sells most of his products online.)


The variety of Koji is differentiated by the seasons at here.

In winter he makes rice Koji, wheat Koji, soybean Koji and Koji for soy sauce making. The rice Koji, which contains mild sweetness and active enzyme, is available the whole year. Black Koji, which uses A. luchuensis on white rice and produces lovely tangi taste, is only available from April to November. This one is loved by the girls who are into making Amazake.  

From natural farming

to Miso and Koji making.

Mr Miyamoto learned to farm by cooperating with the natural cycle at his '20s (now he's at early '40s) and he became officially a farmer. Since he grew soybeans and rice, he started to make Miso and Koji by himself. He says he's still learning about and through nature by farming and making Koji.

My first impression of Mr Miyamoto was a jolly, humorous and clever guy who wears many hats since he broadcasts radio with his friends, writes articles, gets interviews while taking care of his farm and Koji.



Every winter, when Koji and Miso makings are on high season, he gets some helpers and lives together. I was there from 12th to 21st February in 2020. There're a couple of people staying while I was there. We share not only works but also meals, stories and skills. It's a good company. I remember we always laughed a lot even in the busiest season.


The morning tasks were to steam the ingredients and Koji-buta (the wooden trey for making Koji.) and seedling Koji. And the other tasks rise depending on the Koji's cycle. Koji needs around 48 hours to be in the incubator(35-38℃) and we try to keep the temperature stable while Koji raises its temperature by itself. The situation of each Koji is slightly different because of the character of ingredients and the climate of the day. The temperature goes up fast sometimes and slows sometimes. And also we need to take care of some different kinds of Koji at the same time depending on the customer's orders. Yes, it's truly like taking care of Koji which is a living creature. So the role of Koji maker is to be a caretaker and to be involved in the life cycle of Koji. Every day was so different. 


Then the tasks of the afternoon were also depending on the day. Sometimes we had Miso workshops, sometimes we took care of Koji or we weighed Koji for delivering. In the last part of the day, we wash the ingredients and soak them in the water for steaming them the next day. It was fun to wash a huge amount of soybeans while thinking about the Miso workshop happens the next day.

Homemade Miso workshop


The Miso workshop at Miyamoto Koji-ten only happens in winter. Participants can choose how much of Miso they make from 8kg or 12kg.  People mash and mix the ingredients by themselves. 70% of the participants are the repeaters and they say 'We don't want any other Miso but here's.' The sound of making Miso balls and laughs were making a jolly atmosphere and I was sure that Miyamoto Koji-ten will flourish the homemade Miso culture in this area. 


The Koji for the homemade Miso workshop had some choices. 100% rice Koji, 100% soybean Koji, mixing of soybean and rice Koji and 100% wheat Koji. I've never seen the mixture of soybean and rice Koji Miso and wheat Koji Miso.


Aichi Pref. actually is the hotspot of fermented condiments of Japan, such as Sake, Mirin, Miso and Tamari. It's easy to spot the breweries here. On the other hand, it's rare to use soybean Koji for Miso but the Miso in this area is famous for this unique culture. Soybean Koji Miso is called Haccho Miso/ Mame Miso. Some Japanese hate Haccho Miso but the locals definitely have it in the fridge while they also enjoy other kinds of Miso. Aichi Pref. has so many choices.

After the Miso workshop, some participants go on to soy sauce workshop. Mr Miyamoto's wife is actually specialized with soy sauce. She wasn't at the workshop but the participants can get full support of Mr & Mrs condiments'.




What I've learned from the 10 days at Miyamoto Koji-ten.

The reason why I was at Miyamoto Koji-ten was not that I wanted to be skilful on making Koji. I wanted to know the works of Koji maker and the people who're making it. It's easier these days to read and watch about Koji and there're also some online and offline lessons too. Homemaking something is full of joy and learning. So, all those things have encouraged me to know the technic of Koji making at home but still, I want to connect with skilled producers who love their products and their work so that the culture spreads further in distance and farther in the future. They are full of knowledge and have clear sense of making good products.

Although, Mr Miyamoto admits that the image of 'natural', 'traditional' and 'handmade' are always good but at the same time it doesn't always mean it produces good products. Machines also make good and stable products with a good price. He tries his best to follow the natural cycle of Koji and doing every work by hands. And also he sends the Koji to labs to test enzymatic amount and contamination of other kinds of mold. What he works together with is the invisible world of microorganism, so he also balances out between his sense and the scientific figures.

Because of his will, the Miso made of Mr Miyamoto's Koji produce a great flavour and it brings more people to his workshops.

When I asked Mr Miyamoto why he decided to become a Koji producer he went

' I just want to know more about nature.' It was my privilege to be here to work with him and get to know the background of Miyamoto Koji-ten. Thank you so much for having me here. Miyamoto Koji-ten will keep growing with Koji culture. 



Miyamoto Nouen/ Miyamoto Koji-ten
25-1 Ichiba, Nishihazu machi, Nishio city, Aichi Pref.


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