Koji malted grain, which enhances the aroma and umami flavor of traditional Japanese condiments such as miso and shoyu, is made by adding kojikabi (koji mold) to steamed rice or barley.

Indispensable to the production of fermented foods that are basic to Japanese cuisine, koji mold is called “kokkin” (literally, “the national fungus”).

In the Muromachi Period (1336-1573), there were already koji merchant systems in place for the imperial court or the shogunate to control the distribution of koji.

Characters in the Japanese manga series “Moyasimon: Tales of Agriculture” include cute microbes that make people laugh with their tag line, “kamosu zo,” which translates literally as “we’ll brew you.”

The protagonist, Tadayasu Sawaki, comes from a family of mold-starter makers. A first-year student at an agricultural university in Tokyo, Sawaki has the unique ability to see and communicate with microorganisms.

One day, he peers into a container of miso at the university lab and finds yellow koji that used to be at his family’s factory.

Named A. oryzae, the microbe is delighted to be reunited with Sawaki.

He soon discovers more microbes from back home: A. awamori, a black koji, and A. sojae, which becomes unstoppable once it starts talking about umami.

From this manga, I learned that koji comes in many kinds.

At the moment, a different kind of koji, called benikoji, has been attracting attention. Because it turns red when fermented, this koji has been widely used as a dye and more recently as an ingredient in dietary supplements.

It has come to light that two people have died and many others have been hospitalized after taking benikoji supplements made by Kobayashi Pharmaceutical Co.

The pharma company had claimed that the supplements could help lower “bad” cholesterol.

The exact cause of the deaths and health damage has yet to be determined, but the company explained that an “unknown substance” was present in some of the red koji ingredients.

I wonder if a new, hard-to-trace substance was somehow generated.

There is still a lot we don’t understand about molds, even the ones we humans have known for a long time.

Research continues on how we can live longer and healthier, but what should we understand about living safely? I am left deep in thought.

--The Asahi Shimbun, March 28

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Vox Populi, Vox Dei is a popular daily column that takes up a wide range of topics, including culture, arts and social trends and developments. Written by veteran Asahi Shimbun writers, the column provides useful perspectives on and insights into contemporary Japan and its culture.