The only fermented tea in Japan is produced in Ōtoyo Town, located in the mountainous area of central Kochi. It is called Goishicha and its name comes from its similarity to the shape of go (Japanese checkers) stones.
Tea itself was introduced from China originally, but there is no tea in this country that is fermented during production, apart from goishicha. This tea has a distinct sour flavour and used to be exported mainly to the Setouchi region in exchange for salt. As time went by, however, the number of farms producing it dropped drastically, and only a handful of people remembered it until some TV programs and newspapers recently covered its efficacy as a dieting aid. That is why people call it “Tea of Legend”.
Due to contemporary health trends, the goishi tea has come to be used in various ways. People enjoy it in more ways besides drinking alone. For example, mixing the powdered tea into steamed buns or udon noodles, or adding it to rice gruel and so on. I hope goishi tea will live on as a product that revitalizes mountainous regions such as Ōtoyo Town – towns that have been suffering from declining and aging populations.
Taken from vol.18 PDF