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kōji; malted rice; malt; malt-like material from growing mold on rice, barley, beans, etc. (used as a starter to make sake, miso, soy sauce, etc.)
味噌は麹を使って作られます。
Miso is made using koji.
日本酒の醸造に麹が必要です。
Koji is necessary for brewing sake.
麹から作った甘酒を飲みました。
I drank amazake made from koji.