Yu Seki (born September 2, 1992) is a Japanese drummer best known as the percussionist for the rock band King Gnu. Born in Anan, Tokushima Prefecture, to professional musician parents, he began playing electronic drums in childhood. During elementary and junior high school, he attended a dance school and initially aimed to become a dancer, but switched to drums in high school, performing percussion in the school’s brass band. After graduation, encouraged by his parents to pursue his ambitions, he moved to Tokyo. In Tokyo, Seki became active in the live music scene, frequenting session bars where he met bassist Kazuki Arai. He also joined the early lineup of the Tsugaru shamisen duo Kiki. Later, at a music bar, he met Daiki Tsuneta, who was searching for a drummer for his band Srv.Vinci. This meeting led to Seki joining the group, which in 2017 transitioned into King Gnu. The band made its major debut in 2019, quickly becoming one of Japan’s most acclaimed contemporary acts. Outside of King Gnu, Seki is active in various musical collaborations and projects, including appearances such as on the track "SAY LESS"(2025) with Yohji Igarashi.