Toko-koji bed, tana shelves and koji-muro

Three connected scales

Toko, tana and koji-muro name different parts of a Japanese koji-making work area. The toko is the broad bed or table where steamed rice is handled. Tana means shelf: narrow tables set against a room wall can carry shallow trays after rice is moved from the bed. The koji-muro is the enclosing room. These terms should not be collapsed into one vessel or treated as three components found in every brewery.

The bed method and tray-based work are related but distinct arrangements. In toko-koji-hō, the batch is made on a large bed rather than divided into trays or boxes; some forms use one bed throughout, while another arrangement transfers the batch to a separate new bed. In tray-based work, the rice may first be handled on the toko and then divided into shallow trays on the tana.

The bed and its supports

Nada Sake Research describes the toko as a large table or bed. Its technical entry notes that some new-bed arrangements remove insulation and leave spaces between boards for airflow; other forms use a wooden or bamboo lattice set slightly above the surface. These are documented variants, not a checklist for every bed.

The bed method avoids the repeated division of a batch among small trays, while tray-based work allows rice to be arranged and managed in smaller lots. The source cautions that heat and moisture can build near the bottom of a bed, where the rice contacts the wood, so its form affects how the work is managed. The cited glossary gives no single standard construction or measurement for all toko beds.

Shelves inside an insulated room

The tana are narrow shelf-like tables used for trays in the later stages of tray-based koji making. Nada describes them against the koji-muro wall, with trays grouped on the shelves and covered with cloth. The source gives dimensions and spacing for its described arrangement; this page does not generalize those figures to every brewery.

The room makes the bed and shelf work possible in a protected environment. Japan’s cultural-heritage glossary describes the koji-muro as a closed, insulated chamber for keeping conditions steadier than the surrounding building. The Hakushika Memorial Museum of Sake documents rice husks and other insulation, including wall, ceiling and floor treatments and double doors, in one historical brewery. Those materials and details are examples from that building, not a universal design.

What the sources establish

The technical and architectural references support the function and relationship of these features in Japanese brewing: a work bed, tray shelves where that method is used, and an enclosing room designed to protect koji cultivation. They do not establish one origin date for the combined arrangement, a standard room plan, or a universal list of building materials. A photograph of a particular brewery room should therefore be read as evidence for that building, not as a template for all koji-muro.