Rei is a unisex given name of Japanese origin, derived from the kanji "rei" (令和), which means "order" or "good order". It has been used both as a masculine and feminine name in Japan for centuries. Internationally, Rei gained popularity in the late 20th century, particularly in Europe and North America, where it is often associated with Rei Kawakubo, the renowned Japanese fashion designer and founder of the avant-garde label Comme des Garçons. The name Rei is pronounced /ˈraɪ/ in English and has one syllable. It is also used as a surname in Japan.
The name Rei experienced a notable increase in popularity from the late 2010s to early 2020s, with a significant jump from 16 births in 2012 to 27 in 2016 and peaking at 48 births in 2020. However, there's been a decline recently, with 33 births in 2021 and 27 in 2022.