Japanese natto has a long history, with some research suggesting it has been around for thousands of years. The first book in which the word "natto'' was specifically described as "stringy natto" is said to be a collection of fables written in the 15th century, "Otogi Zoshi - Shojin Gyorui Monogatari."
Later, in the 17th century, as urbanization progressed, especially in the Edo (present-day Tokyo) area, a diverse food culture blossomed, and natto sellers became part of the daily scene and became popular with the common people.
Hundreds of years have passed since then, and natto is still loved by many and is an essential part of the Japanese cuisine.

How Long Have People Been Eating Natto?