For a long time since, until the Muromachi period, koji production was operated by specialists who were independent from sake traders because of its importance for the process of sake brewing and the supply and demand for other foodstuffs such as miso and soy sauce.
以来、永らく麹造りは、酒造りの工程に占める重要性と、味噌や醤油など他の食品への供給需要から、酒屋業とは別個の専門職として室町時代まで営まれてきた。