Vigna angularis is a small, herbaceous annual vine in the family Fabaceae, widely known as the adzuki bean, azuki bean, or red mung bean. It is native to East Asia, with a center of genetic diversity in China and Japan, where it has been cultivated for at least 3,000 years. The genus name Vigna honors the 17th-century Italian botanist Domenico Vigna, while the species epithet angularis refers to the slightly angular or "squared-off" shape of the bean's ends. Historically, the adzuki bean has held a prestigious status in East Asian cultures, often associated with good fortune and protection, and it remains a vital pulse in the agricultural and spiritual traditions of Japan, Korea, and China.

The plant is characterized by its bushy or twining growth habit, trifoliate leaves, and bright yellow flowers that give way to cylindrical pods. It is well-adapted to the temperate and subtropical climates of East Asia, preferring well-drained soils and moderate rainfall. Like other members of the Fabaceae family, Vigna angularis possesses root nodules that house nitrogen-fixing bacteria, allowing it to improve soil quality and serve as an effective rotational crop. While primarily grown for its seeds, the plant’s foliage is occasionally used as a high-protein forage for livestock in traditional farming systems.

Vigna angularis is unique among legumes for its frequent application in confectionery and sweet dishes. The beans are boiled, sweetened with sugar or honey, and mashed to create a smooth or chunky paste known as anko (in Japan) or hongdousha (in China). This paste serves as the primary filling for traditional sweets such as mochi, dorayaki, and manju. In savory contexts, the beans are cooked with rice to make sekihan (red bean rice), a dish traditionally served at celebrations and milestones. The beans are prized for their mild, nutty flavor and a texture that becomes creamy and soft when cooked, without the strong "beany" aftertaste common in other pulses.

Nutritionally, adzuki beans are a dense source of plant-based protein, complex carbohydrates, and dietary fiber. They are particularly rich in micronutrients such as potassium, magnesium, and folate. The beans contain a variety of bioactive compounds, most notably a high concentration of proanthocyanidins and other polyphenols, which contribute to their deep red color and provide potent antioxidant activity. They also contain alpha-galactosidases, complex sugars that can cause flatulence if not properly processed through soaking or long cooking. Additionally, adzuki beans have been studied for their potential to inhibit alpha-glucosidase, an enzyme involved in carbohydrate digestion, which may assist in regulating blood sugar levels.