> Natto is a traditional Japanese fermented food that is sticky when eaten and clings to the mouth and chopsticks (Fig. 3c). Natto is made by fermenting soybean

> Natto is a traditional Japanese fermented food that is sticky when eaten and clings to the mouth and chopsticks (Fig. 3c). Natto is made by fermenting soybeans with the spore-forming bacterium Bacillus subtilis, which can survive dry conditions. As expected, in this study, we observed the large white colonies formed by B. subtilis. According to the questionnaire, 9% and 27% of the participants have eaten natto daily and weekly, respectively; 19% of the participants ate natto during the experimental period. The participants who ate natto had a significantly higher incidence of large white B. subtilis colonies on both sides of the masks than those who did not. The authors have this bizarre obsession with reminding us of all the Japanese things going on in the study, and it culminates in borderline parody here.