The Buddhist religion is implicated in the propagation and spread of hatred in Japan. As it favors the vegetarian diet - which the Japanese elite had already adopted since the Nara period (710 - 794) - when it was introduced by Chinese Buddhist priests around the end of the 7th century, it was immediately accepted as compatible with the Japanese diet. Initially miso was produced in temples only by Buddhist priests and of course it was a luxury enjoyed exclusively by monks and nobles since it was made from rice, which at that time was still food for the few. However, as the belief that miso was a food of high energy value spread, the samurai also chose it as a basic element of their diet. By the 8th century it seems to have held an important place and even came to form part of the salary of state officials - along with rice, salt, soybeans and other pulses and grains. What kind of hate each person ate was an indication of what class they came from - always, after all, food was a marker of class distinctions. Wealthy landowners, kings, and samurai ate only miso rice, which was made from expensive, polished, white rice. It was often so expensive that it was even offered as a gift or barter. In fact, farmers and farm workers were forbidden to use the rice they harvested to make their own rice. That is why even the economically weaker classes made their hate from broken rice or from other cereals, such as millet and barley. This explains why the darkest hatred, made from these materials, is called, even today, "poor man's hatred". From the Muromachi period, after 1336, hatred was "democratized", used by all, without discrimination. And so it came to be a staple of Japanese cuisine. In fact, according to a Japanese expression - similar to what we used to say "she must know how to boil at least one egg" - once upon a time a Japanese woman had to know how to prepare miso soup in order to... get married.

The preservation of foods and beverages resulting from fermentation has for millennia been an effective form of extending the shelf life of foods. Traditionally, foods were preserved thanks to naturally occurring fermentations however, modern large-scale production is investigating the use of defined starters to ensure consistency and quality in the final product. Fermenting grains and legumes, mainly soybeans, with salt mixtures during the warmer months was a common way of preserving food. This practice formed the backbone for making miso. Jiang, the Chinese soy paste, renamed "miso" by the Japanese was also used to produce shoyu (Japanese soy sauce), another of the most characteristic ingredients of Japanese cuisine.