Nattō is a traditional Japanese food made from soybeans fermented with Bacillus subtilis var. Some eat it as a breakfast food. It is served with soy sauce, karashi mustard and Japanese bunching onion. Natto is the highest dietary source of vitamin K2 (the potent MK7 variety) with a huge 850mg per 100 gram serving (1000%+ of your RDA).
It is widely eaten in Japan which has the highest longevity rate in the world. There is an exact Thai equivalent of Natto, it’s called Thua nao. Available all over northern Thailand.