The newspaper reported that more people are working at home during the pandemic, driving up demand for robusta coffee beans, which are mainly used to make instant coffee.
Meanwhile, sales of the higher-quality arabica beans favoured by coffee shops have fallen.
The trend has made Vietnam, the world’s top robusta maker, Japan's top supplier of coffee beans and relegated Brazil to second place.
Japan's state of emergency, declared in early April, shuttered cafes and restaurants across the country, forcing Starbucks Coffee Japan to halt business at some 1,100 outlets. The closures dealt a heavy blow to demand for arabica beans.
In contrast, demand for robusta, a cheaper and more bitter variety used in instant coffee products, has been strong as COVID-19 restrictions keep people at home.
Demand for instant coffee has spiked. Sales of instant coffee products in the second quarter grew about 10 percent from a year earlier, according to food processor Ajinomoto AGF.
Changes in consumption patterns have also affected Japan's imports of unroasted coffee beans.
Trade data show that Vietnam was the top seller of unroasted beans to Japan for the first seven months of 2020. A total of 67,392 tonnes of unroasted beans were imported from the Southeast Asian country during the period, up 26 percent year on year.
Meanwhile, imports from Brazil, mostly arabica beans, plunged 40 percent during the period to 63,850 tonnes.
This was the first time Japan’s imports from Vietnam outpaced those from Brazil.
The Nikkei Asia Review quoted Shiro Ozawa, an adviser with Tokyo-based specialty coffee trader Wataru & Co., as saying that Vietnam is on track to top Brazil for the entire year and that this is a historic moment.