Zanthoxylum piperitum, commonly known as Japanese pepper or sansho, is a flowering plant in the Rutaceae family. It is native to East Asia, particularly Japan, Korea, and China. The plant is characterized by its aromatic leaves and small, greenish-yellow flowers, which develop into small, round fruits that are often used as a spice. The leaves and unripe fruits of Zanthoxylum piperitum are used in traditional cuisine, imparting a unique, citrusy flavor with a numbing sensation. This spice is a key ingredient in various dishes, including soba and yakitori, and is valued for its culinary and medicinal properties.