Citrus × junos is a small, aromatic citrus tree in the family Rutaceae, commonly known as yuzu. It is a hybrid, most likely derived from a cross between Citrus ichangensis and Citrus reticulata, and is native to East Asia, particularly China and Korea, though it has been most extensively cultivated in Japan for centuries. The genus name Citrus comes from Latin, historically referring to citron-like trees, while the species epithet junos derives from a latinized form of the Japanese name yuzu (柚子). The fruit was introduced to Japan where it became culturally and culinarily significant, prized for its intense aroma and tart flavor.

As a food source, Citrus × junos produces small, round to slightly oblong fruits with yellow to greenish skin when ripe. The juice and zest are highly aromatic, rich in citric acid, and used primarily as a flavoring rather than eaten fresh. Yuzu is a key ingredient in Japanese cuisine, featuring in sauces such as ponzu, garnishes for sashimi, seasoning for soups and hot pots, and in sweets and beverages. It is also employed in Korean cuisine, especially in yuja-cha, a preserved yuzu tea, and in various marinades and condiments. The zest and peel are used to extract aromatic oils for culinary and sometimes cosmetic purposes, while the acidic juice adds brightness to dishes.

Chemically, Citrus × junos contains high levels of citric acid, which imparts its characteristic sourness, and essential oil components such as limonene, γ-terpinene, and linalool, which give the fruit its signature citrus aroma. The peel contains flavonoids including hesperidin, naringin, and other polymethoxylated flavones, which contribute antioxidant and anti-inflammatory properties.