Tamba-Sasayama Black Soybeans

Tanba-Sasayama kuromame is the black soybean of Tanba-Sasayama City in Hyogo Prefecture, grown in the area's particular climate and soil, and the largest-grained among black soybean varieties. JA Tanba-Sasayama, the local agricultural cooperative, handles these beans alongside other local products such as Koshihikari rice and carries the Tanba-Sasayama name across the country. Many people first meet the bean at the table: it is a fixture of New Year osechi dishes, and through the rest of the year it is slow-simmered into nimame. To see why the bean is bound so closely to Tanba-Sasayama, it helps to walk into the fields where it grows and watch how people raised it under a shortage of water.

Black soybean growing in Tanba-Sasayama reaches back roughly three hundred years. One traceable thread appears in Ryori Momoku Chomisho, a cookery book published in 1730 (Kyoho 15). It notes that "black beans are a specialty of Tanshu Sasayama" and that the black beans of Tanshu Sasayama are good simmered and steeped — marking them, even then, as a prized specialty with real market value. The glistening simmered bean on a table today and the named specialty in that Edo-period book point to a crop from the same ground.

Light rainfall and short irrigation water around Tanba-Sasayama wrote themselves straight into how the bean is grown. To stretch the little water available, villages would leave some paddies unwatered as giseiden, or "sacrifice fields"; they dug up and sun-dried the field soil in a method called horisaku; and they heaped it into tall ridges for the crop, a practice known as high-ridge cultivation. None of this could be done by a single household alone — people sharing one water system had to talk it through and divide the work. Turning fields that could not be irrigated into dry, high-ridged ground is where Tanba-Sasayama's black soybean took root.

A good bean starts with good seed, the other edge that sets this crop apart. Farmers selected large, dependable seed to keep back, generation after generation. Between the late Edo and Meiji eras, Habe Rokubei and his son Habe Motojiro put real effort into breeding and spread a black soybean known as Habe-guro. That seed work did not stay with individual farmers: agricultural experiment stations carried it on, and today a seed-production council continues it, with local public and private bodies together maintaining the bean's genetic stock. Behind one ordinary-looking black bean stands generation after generation of choosing and keeping seed.

The crop's planted area shows how this growing region took shape in modern times. In 1960 (Showa 35), the city's Tanba-kuro covered only about 10 hectares. After the rice-acreage reduction policy began in 1971 (Showa 46), black soybeans were brought into the paddies as an income crop in place of rice, and the area climbed to about 777 hectares by 2019 (Reiwa 1), counting the green-soybean (edamame) use. For the dry-bean Tanba-kuro alone, Tanba-Sasayama City grows around 557 hectares, close to a fifth of the national area. Holding that scale up are the growing skills built from horisaku, together with joint pest control and shared machinery and facilities run through the production cooperatives — a habit of a whole settlement helping one another.

Back at the table, Tanba-Sasayama kuromame holds two clear places. The first is New Year: the dish of glossy simmered black beans in an osechi spread calls for large black soybeans like these. The second is everyday: across the whole year, the beans are slow-cooked into nimame, a home preparation tied to no season. A New Year nicety on one hand and a plain simmered pot on the other, the large bean arrives at both in its simplest cooked form. Set back against the fields of Tanba-Sasayama, that bowl of simmered beans connects to the high ridges, to the farmers who chose the seed, and to the cooperative work of the whole settlement.

The land where Tanba-Sasayama kuromame grows carries a long local history of its own. People have lived around Sasayama since the Jomon period, through Yayoi and Kofun times — the great Kumobe Kurumazuka tumulus points to a group here tied to the central powers. In 1609 (Keicho 14), Sasayama Castle was built by order of Tokugawa Ieyasu, and the castle town with the surrounding Taki district formed one complete region once called the "capital of Tanba." The old quarter keeps armor, lacquerwork, and paintings, along with fine Ojiyama ware first fired as the Sasayama domain kiln in the late Edo period; the former Sasayama District Court, built in 1891 and among the oldest wooden courthouse buildings in the country, now serves as the municipal history museum. Read the castle town and the ridged bean fields just outside it together, and the name Tanba-Sasayama holds both the fields and the castle.