Gugudan

Pre-debut

In January 2016, Nayoung, Kim Se-jeong and Kang Mi-na were introduced as Jellyfish Entertainment's first female trainees on the Mnet survival show Produce 101 where 101 female trainees from various companies competed to debut in an 11-member girl group that would promote for a year under YMC Entertainment. After placing 2nd and 9th respectively in the final episode, Sejeong and Mina eventually debuted as members of I.O.I in May 2016.

2016: Debut with Act. 1 The Little Mermaid

Despite denying earlier reports about Sejeong and Mina debuting in a 3-member girl group in June, Jellyfish Entertainment confirmed on June 7 that the two I.O.I members would debut within the month in what would be the company's first girl group. Because of YMC Entertainment's special terms in which I.O.I's members are allowed to do activities under their respective companies while I.O.I was on break or while the group promoted in sub-units, there were no complications with the plan.

Nayoung was also confirmed as a member on June 10 and on June 13, Jellyfish Entertainment revealed that Gugudan would be a 9-member group. On June 17, Jellyfish Entertainment announced the group name.

On June 22, the group confirmed that they were going for a "mermaid" concept. Following the announcement, a highlight medley of the group's debut mini-album was released on June 24 and they eventually debuted, on June 28, 2016, with the mini-album, Act. 1 The Little Mermaid, with "Wonderland" as the title song. The song's music video was released online via a live countdown on the Naver V App.

Gugudan participated in Jellyfish Entertainment's yearly winter project, Jelly Christmas 2016, with their label mates Seo In-guk, VIXX, Park Yoon-ha, Park Jung-ah, Kim Gyu-sun, Kim Ye-won and Jiyul. The title track, "Falling" (Hangul: 니가 내려와) was released digitally on December 13, 2016.

On December 17, 2016, Gugudan announced their official fan-club name, "Dear Friend" (Hangul: 단짝), through their V app channel. The fan-club name means that the fans and Gugudan are going to be best friends.

2017–present: Act. 2 Narcissus

On January 20, 2017, it was reported that gugudan was set for a February comeback. On February 3, 2017, Jellyfish Entertainment announced that Gugudan would make their first comeback since debut with their second mini-album, on February 28. On February 24, 2017, Jellyfish Entertainment announced that the release of the album was changed to February 27. Gugudan released their second mini-album Act. 2 Narcissus and its title track "A Girl Like Me" (Hangul: 나 같은 애), on February 27, 2017.

Members