Yuzu (柚子) is a citrus fruit and plant in the family Rutaceae of East Asian origin. Yuzu has been cultivated mainly in East Asia, though it has also recently been grown in New Zealand, Australia, Spain, Italy, and France.

This fruit resembles a yellow clementine with uneven skin and can be either yellow or green depending on the degree of ripeness. Yuzu fruits, which are very aromatic, typically range between 5.5 and 7.5 cm (2+1⁄8 and 3 in) in diameter but can be as large as a regular grapefruit (up to 10 cm or 4 in, or larger).

https://en.wikipedia.org/wiki/Yuzu