Rei is of Japanese origin, meaning "good", "wisdom" or "spirit". It is commonly used for both males and females, reflecting its versatile nature. In Japan, Rei is often used as a unisex given name, but it can also be found in other cultures around the world.
The name Rei experienced a significant increase in popularity between the years 2015 and 2021, with a total of 186 births during this period compared to only 70 births from 1987 to 2014. The peak occurred in 2021 with 34 births, followed by 30 in 2019 and 28 in 2018. However, it is important to note that the overall trend appears to be declining since 2017.