In Japanese, the characters for soybean literally mean "great bean," indicating its place as the nation's most important legume. There are hundreds of varieties of soybean in Japan, coming in various sizes and colors.

In Japan, yellow soybeans are the most common, but they actually come in various varieties including white, black, red and green.

Soybeans are also classified by size: large, medium, and small. The large size are used for dishes such as simmered soybeans, while the medium size are used for processed foods such as tofu, miso, and soy sauce. The small ones are used for natto (fermented soybeans).

Some people think that the popular healthy Japanese snack edamame, are a particular type of bean, but they are simply immature soybean pods. These are harvested when green, a month before the pods mature and becomes brown and dry. Various soybean varieties including yellow, green, and black are eaten as edamame.

Classification: Fabales (order), Fabaceae (family), Glycine (genus) [annual]
Scientific name: Glycine max
Other names: Soy, soya bean, edamame
Origin: China (possibly also East Asia or India)
Flowering season: May to August (small flowers measuring 2cm)
Height: About 60cm to 180cm

The height, flowering season, and flower color vary depending on the variety, which range from early (summer) to late (fall) varieties.

Yellow soybeans

The yellow soybean is the most common in terms of production quantity and varieties. Most processed soy products such as miso, tofu and natto are made from medium or small yellow soybeans.

Green soybeans

The peel of this soybean is green. It is often used to manufacture soy flour (kinako) or to make simmered soybeans, and in recent years is found in green soybean tofu and green soybean natto.

Black soybeans

The black soybean is generally used to make simmered soybeans, often eaten as a part of the traditional Japanese New Year meal. Although harder to find, black soybean tofu and black soybean natto are also available.