Gugudan, also known as gu9udan or gx9, was a popular eight-member K-pop girl group managed by Jellyfish Entertainment. They made their debut on June 28, 2016, with their mini album "Act. 1 The Little Mermaid". The group's name, which means 'multiplication table' in Korean, symbolized the nine unique charms of each member. Prior to their debut, members Nayoung, Sejeong, and Mina gained recognition on the survival reality show Produce 101, ultimately leading to Sejeong and Mina joining the final lineup of I.O.I. Over the years, the group also formed subunits like Gugudan 5959 and Gugudan SeMiNa to showcase different member combinations. Unfortunately, due to personal reasons, Hyeyeon left the group in October 2018. One of their members, Sally, gained attention by participating in the Chinese version of Produce 101, eventually becoming a member of the temporary girl group BonBon Girls 303. Despite their talent and success, Jellyfish Entertainment announced the end of Gugudan's activities on December 31, 2020, marking the conclusion of their remarkable journey in the K-pop industry.