The Buddhist priest, Kakushin of the Shinshu area brought the recipe for miso to Japan from Song, China in 1250. Then the liquid which accumulated at the bottom of a cask was discovered to be good for cooking food. With great effort and repeated testing, it was made into tamari soy sauce. It is believed that the word shoyu (soy sauce) was already being used in 1520.

In the early years of the Edo period, shoyu was the same as tamari soy sauce, but from the Genroku period to the Kyoho period (1688 to 1736), as the population of Edo (an old name for Tokyo) increased, and Edo's culture became prosperous, many modifications and tests were done in an attempt to satisfy Edo people's tastes . As a result, the modern-day koikuchi shoyu (strong-flavored soy sauce) which is made from soybeans and wheat, was produced.