Koji-buta (shallow wooden trays for koji) are one of the tools used in Japanese sake brewing and used at the koji making stage of Japanese sake. It is also called as 'moro buta' (moro lid).
Intricate manual techniques that do not rely on machines are required when brewing expensive Nihonshu (Japanese rice wine) ginjo sake (sake made from rice grains milled to 60% or less of original weight), and koji-buta are box-shaped tools used to divide the koji when using the futakoji method. It is abbreviated as 'futa' (lid) in the lingo of sake brewery workers.
Koji-buta are made from straight-grained fir and are approximately 45cm in height by 30cm in width by 5cm in depth. This can contain about 1.8 liters worth of rice koji. This is to divide rice into smaller proportions of approximately 1.8 liters to cool it down while monitoring its progress.
Koji-bako (wooden boxes for koji-making)
Hakokoji (box koji) is a simplified version of the futa-koji method and uses a larger version of the koji-bako, and is called 'hako' (box) in the language of sake brewery workers. This tool is suited for mid level sake.
Koji-doko (wooden chest for koji making)
The simplified hako-koji method called toko-koji (floor koji) does not use a box but spreads the steamed rice on top of a huge counter placed in a koji culture room, where koji spores are spread on it, and it is cooled down while still on the counter as in the futa-koji method for making nihonshu. This counter is called kojidoko (yeast floor) and brewery workers simply call it 'toko'. This is suited for average sake.