Sekai has two separate sources: in Japanese it is the word for "world", and in Shona, the main language of Zimbabwe, it is a traditional name meaning "laughter" or "laugh", usually given to girls there. In the United States it is used for boys and has the breezy sound of Kai and Kairo. Sekai had fewer than five births in 2000, ranked number 13711 in 2015, climbed quickly after 2021 and reaches its best rank, number 2444, in 2025 with 56 boys.