Natto is a traditional Japanese fermented food with a unique smell and stickiness. In 2020, the National Cancer Center announced that high consumption of natto lowers mortality risk. Natto not only activates the immune system, but also contains a significant amount of vitamin K2, which can suppress brain inflammation, while the substance responsible for its stickiness lowers blood sugar levels. We report the latest findings on the health benefits of natto, which is drawing attention worldwide.