Fermented foods are popular among young people right now. The size of the natto market has reached a record high, and the number of restaurants and cafes using fermented foods is quickly increasing. "Fermentation girls" who dearly love fermented foods for beauty and health have emerged. Japan has created a wide variety of fermented foods, from traditional seasonings that have many local flavors such as soy sauce, miso and fish sauce to over 3,000 kinds of pickles. Foreigners get excited over the smells that you need to get accustomed to, solid umami, and intense acidity. We investigate the fermentation culture of Japan.