Kep1er is a K-Pop girl group from South Korea, formed through the 2021 survival competition TV show Girls Planet 999. The group was put together by South Korean entertainment and mass media company CJ E&M, and is made up of nine members: leader Choi Yu-jin, co-leader Mashiro Sakamoto, Kim Chae-hyun, Huening Bahiyyih, Kim Da-yeon, Seo Young-eun, Kang Ye-seo, Hikaru Ezaki, and Shen Xiaoting. The group was spawned from the Girl Planet 999 competition series, which aired from August 6 to October 22, 2021. The show had the participation of 99 contestants from China, Japan, and South Korea. Several of the final 9 were already active in the entertainment business, such as eventual leader Choi Yu-jin, who was already part of the girl group CLC. Once formed as Kep1er (the name deriving from Johannes Kepler and his laws of planetary motion), the group made their debut with the single “Wa Da Da,” which hit the Billboard Global 200 chart at Number 117, as well as Number 16 in Japan, Number 11 in Singapore, and Number 13 in the US World Digital Songs Chart. “Wa Da Da” was followed by the group’s debut EP, titled First Impact, which hit Number 1 on the Gaon Albums Chart.