The origin of natto is not entirely clear and to this day arouses the curiosity of historians and lovers of Japanese cuisine. According to the most popular legend, the dish was discovered entirely by accident in the 11th century by the warrior Minamoto Yoshiie, who, during a military expedition in northern Japan, ordered his men to cook soybeans for the horses. To make transport easier, the hot beans were placed in a sack of rice straw and tied to a horse’s back. After a few days the soy changed its texture, began to stretch into strands and had an intense smell. To the warriors’ surprise, it turned out to be tasty and exceptionally nourishing, and so natto was born.
It was probably the warmth of the horse and the bacteria present in the rice straw that started the natural fermentation process, in which the characteristic enzyme nattokinase was formed. From that moment natto began to spread across Japan, becoming one of the symbols of traditional cuisine and a healthy lifestyle.
According to the Soy Info Center:
“According to legend, it was discovered accidentally in northeast Japan by Minamoto (Hachimantaro) Yoshiie when warm, cooked soybeans, placed in a rice-straw sack on the back of a horse, turned into natto.”
You can read more about the history and culture of natto here: https://www.soyinfocenter.com/books/151
