Koji Tray (Morobuta/Kojibuta) Size S - Locally Made, 100% Natural Japanese Cedar Wood

Koji Tray (Morobuta/Kojibuta) Size S - Locally Made, 100% Natural Japanese Cedar Wood


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What is Koji Tray (Morobuta/Kojibuta) Size S?

Koji tray small size is a professional-style container that is ideal for making koji at home. Called kojibuta or morobuta in Japanese, the koji tray is the proper tool to make koji. This product is currently hard to find in the market.

Crafted with Japanese cedarwood, this product is constructed by hand, one part after another by skillful artisans. This product has the perfect size for our Household Koji Fermenter PF100-48H. One fermenter has three sections, and each S-size koji tray can fit into one section of the fermenter.

Koji Tray Size S

Uses “Nagara Cedar” from Gifu Prefecture

Nagara cedar refers to cedars produced in the Nagara River basin in Gujo District and Takegi District of Gifu Prefecture. The name means “long and good cedar”. Cedar is suitable for koji because it has no natural antibacterial effect like cypress.

Nagara Cedar for Koji Tray

One Koji Tray Can Make Up to 1kg of Rice Koji

You can make up to 1kg of rice koji in one container with an S-size lid. Combined with Household Koji Fermenter, you can make up to 3 kg of rice koji at a time.

Up to 1kg of Rice Koji in Koji Tray

No Preservatives Used

No preservatives are applied to general building materials. You can use it safely.

Koji Tray with No Preservative Used
Board Thickness

Suitable Design for Koji Fermentation

Specially designed with a slightly lifted center based on the tray used by koji maker professionals, making the koji easily spread on the tray's surface. This is important to avoid uneven heat distribution that can ruin the yeast propagation process during koji making.

Koji Tray Variations with Suitable Design

It is an easy-to-use tray diligently crafted with a wood planer to have smooth finishes.


We are pleased to inform you that Koji Tray (Morobuta/Kojibuta) Size S - Locally Made, 100% Natural Japanese Cedar Wood is now available on Amazon USA. Click the link to see the product!


Koji Tray Size S Details

Jiuqu lid S size
  • 1. 26cm
  • 2. 19,5 cm
  • 3.4 cm
  • 4. 28cm
  • 5. 21,5 cm
  • 6. 5,5 cm

Koji Tray Size Variations

How to Take Care of Koji Tray

● Koji tray is made of wood, therefore do not store in humid places for it can cause mold to grow.

● If you find mold growing on your koji tray, try wiping it off with rubbing alcohol or shochu with high level of alcohol.

● If the mold is already growing too deep, scrape it off.

Koji Tray Variations with Suitable Design

Tips: After each use, hand-wash with water and then wipe thoroughly with clean cloth. Let dry in a well-ventilated room. Do not use detergent and dishwasher for cleaning.

Role of the Koji Tray

Koji Tray, commonly known as kojibuta, is a small container that has been used for a long time in koji making (the process of propagating yeast cells on steamed rice).

Koji tray is the suitable tools to make rice koji, brown rice koji, soybean koji, barley koji, etc.

Koji making takes place in a hot and humid specialized room called Kojimuro, which takes 48 to 56 hours. However, due to the nature of the room, various parts like the center and corners, front and back, whether it's close to the ceiling or near the tatami floor, can have different temperatures and humidity.

Therefore, the rice is divided into small portions on this koji tray. The lid placement is regularly moved to adjust the rice condition to be the same in terms of temperature and humidity.

By moving and reloading every 3 hours, lids stacked in the room's corners are moved to the center. The lids in the back are moved to the front, and lids stacked in the upper row are moved to the lower row. By doing this, the yeast cell will be uniformly propagated in the rice koji.

Advantages of koji tray method:
● Compared to machine-made koji (manufactured by automatically controlling the heat generation of koji), the finish of koji is much better. Even in sake breweries, when it comes to sake in junmai or ginjo classification, most of the breweries are made using this lid method. After all, there are some aspects of brewing that are not yet understood by the power of science or machinery.

● The koji finish affects not only sake but also miso and soy sauce. The koji, which is of good quality even after the preparation, works well.

Disadvantages of koji tray method:
● Controlling the temperature. Because temperature control is difficult, it takes more energy and attention.

● A large number of koji tray requires more labor.

How to Make Rice Koji

In this video, we will explain the steps to making Rice Koji (fermentation starter, Aspergillus oryzae, bred on rice). Rice Koji manufacturer generously hands down this guide. Please feel free to use this as a reference when making Rice Koji.

How to Make Rice Koji
How to Make Koji Rice Thumbnails
Koji is steamed grains which have koji starter mold grown on them. It is a treasure house of enzymes, and it decomposes grains into amino acids, vitamins, minerals and more. Making Rice Koji is not only fun and economical; you get to know exactly what ingredients are being used in the process. Follow our easy 11 steps and get Koji-making!
Recipes that uses Rice Koji
How to Make Amazake Thumbnails
Amazake (Sweet Sake) is a Japanese energy rice drink made from koji (Aspergillus Oryzae) and rice. It is known for its health benefits since the Japan's Kofun Period. We will learn how to make homemade Amazake in two recipes. Let's try it at home and sip your own Amazake!
How to Make Miso Thumbnails
Miso (みそ or 味噌) is a traditional Japanese seasoning produced by fermenting soybeans with salt and koji (the fungus Aspergillus oryzae), sometimes added with rice, barley, seaweed or other ingredients. The result is a thick paste-like substance. Nowadays, miso is gaining worldwide interest.
Shio Koji
How to Make Shio Koji Thumbnails
Shio Koji, also known as Salt Koji, is made up of rice koji, salt, and rice. Shio koji has been widely used in Japan with ancient origins as a seasoning or ingredient, particularly for fermented foods. Learn how to make shio koji, at the comfort of your abode!

The Amount of Koji Rice And The Amount of Rice to Use

The Amount of Rice

The Amount of Finished Koji Rice (Approximation)

koji rice quantity
koji rice quantity
koji rice quantity
koji rice quantity
koji rice quantity
koji rice quantity

How to Make Barley Koji

In this video, we will explain the steps to making Barley Koji. Barley koji is used as the raw material for making Japanese fermentation food such as barley miso (麦味噌), kinzanji miso, and shoyu. At the sake brewery, barley koji also used to make barley shochu (麦焼酎). This recipe is an instruction from a Japanese koji manufacturer summarized by Kawashima the Japanstore. Please use this as a reference to how to make barley koji.

How to Make Barley Koji
How to Make Barley Rice Thumbnails
Barley koji is one type of koji, made by cooked barley that has been inoculated with koji mold (koji kin). With barley koji, you can make various foods, such as barley miso.

In this article, we will explain how to make barley koji (using koji starter, in this case, Aspergillus oryzae, inoculated on wheat/barley). We hope that you can make nice barley koji!

Other Tools to Use When Making Koji

Choosing the right tools will help you produce successful koji, an ingredient responsible for making Japanese fermented foods like Miso, Amazake, Sake, Shoyu, Mirin, etc. To help you produce successful koji, we provide other tools that you can use along with Koji Tray Size S. Check our recommendation products below:

Polypropylene Cloth for Small Koji Tray

Polypropylene Cloth for Koji Tray

Make good-quality homemade koji using the cloth favored by koji maker professionals. Mat cloth from Polypropylene fabric prevents the spillage of raw ingredients. It also optimizes the humidity & temperature to keep the koji warm at the right temperature and smoothly finish the fermentation.

Measurement: (44 × 46 cm)

Click here view product

Cotton Cloth for Small Koji Tray

Cotton Cloth for Koji Tray

This bleached cloth is manufactured by Yoshida Textile, a specialty store for food and textile located in Tsubame City, Niigata Prefecture, that was established in 1936. You can use this 100% local Japanese cotton cotton to make koji.

Measurement: (40 × 70 cm)

Click here view product

Customer's Voice

I made a koji tray in my way and failed. Koji tray made by craftsmen are different.

The surface of the wood is so smooth that it feels good, and the wood are firmly fitted. I regret that I should have ordered from the beginning. Thank you for the excellent product. (Wanta, 40s)

I bought it to make koji for miso and amazake.

Since it is made of wood, the temperature doesn't rise too much, and it is straightforward to use because it can keep the moisture moderately, and the quality of the koji was also outstanding.

The size was easy to use for home use as it could be made from 1kg of koji to 3.0kg.
(Really, 50s)

I used to use rice koji and plastic squid, but I think that's the reason why it doesn't work.

I guess that cedar trees are suitable for making koji because of their antibacterial properties and breathability, so it's still different. I will challenge using this. (Fermented Boys, 40s)


● This product is made with natural material, therefore the wood grain and color may be different in each koji tray.

● Wood grain may very greatly from item to item. Customers is asked to refrain from selecting products. We appreciate your understanding.

Product Details
Size 28 cm x 21.5 cm x Height 5.5 cm
Material Cedar Wood
Koji Tray S

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