Kira Sung is a professional jiu-jitsu athlete and a black belt under Hyuk-il Kwon of the Seorae Academy in Seoul, South Korea. Although already successful on the international grappling circuit, Sung's first major breakthrough performance took place at the International Brazilian Jiu-Jitsu Federation (IBJJF) World Championship in 2018, a tournament Kira won, then becoming the first Korean competitor to conquer world title in this sport.