Girls Planet 999 () is a 2021 South Korean reality competition show created by Mnet. It premiered on August 6, 2021, and was originally broadcast every Friday at 8:20 PM KST for the first eleven episodes until its finale on October 22, which was broadcast live at 8 PM KST. It was aired on the Mnet channel, IQIYI, AbemaTV, tvN Asia, or YouTube depending on the viewer's region.
A production by Mnet's parent company CJ E&M and its subsidiary Studio Take One, as well as in collaboration with game developer and publisher NCSoft, the aim of the competition was to debut a new 9-member K-pop girl group consisting of trainees and idols from China, Japan, and South Korea. Auditions for the competition were held from January to February 2021.
Out of 13,000 applicants, 99 final contestants were selected. These 99 contestants were split equally into three groups; the -Group, -Group and the -Group.
In the finale on October 22, 2021, which was broadcast live, the show announced the final 9 members who would debut as Kep1er.
A second season named Boys Planet featured an all male contestants premiered on February 2, 2023 featuring male trainees and idols.
The "planet" theme of the show was derived from a new collaboration between Mnet and NCSoft's new platform called Universe which is centered around K-pop. It allowed votes from other countries outside of the participating three, and also hosted other promotional content for the show.
The show initially grouped the girls into groups of 3 which were called "cells." An entire cell of girls could be eliminated all at once, hence increasing the risk of elimination. To counteract this, the "Planet Top 9" is introduced. Contestants who are selected or voted to be the Planet Top 9 (designated P1 to P9) can reorganize cells to try and lower the chances of elimination. Cells were disbanded after the first elimination round. At the end of the competition, the top 9 most-voted contestants debuted regardless of nationality.
The show, as well as its auditions, was first announced on January 11, 2021, through Mnet. Yeo Jin-goo was announced as the show's presenter on June 8, followed by the reveal of the mentors and the name of the show's opening theme later that same month. More promotional clips from the show were broadcast that month on Mnet.
The show's premiere date of August 6, 2021, was confirmed through a teaser video released on July 6, 2021. Another teaser video showcasing the faces of the 99 contestants was released on July 8, along with a promotional poster.
The theme song, "O.O.O (Over&Over&Over)," was released on July 12, 2021, accompanied by a performance by the Korean group with Kim Dayeon as Center. Another version of the performance featuring the Chinese group was released on July 14 with Shen Xiaoting as Center. The Japanese group's version was released on July 16 with Hikaru Ezaki as Center. The full version containing all three groups was released on July 29 during M Countdown, preceded by the contestants' profiles which were released from July 17 to 19 at 10 AM KST for each group. More teasers were released in July and August 2021 leading up to the show's premiere.
The show was available through Mnet in South Korea, iQIYI in China, AbemaTV and Mnet Japan in Japan, tvN Asia in Southeast Asia, and YouTube in the rest of the world through Mnet's YouTube channel, Mnet K-POP.
The series was presented by Yeo Jin-goo, dubbed as the "Planet Master." The rest of the mentors, also dubbed as "masters," were:
There was a total of 99 contestants participating in the competition. 33 were Korean, and 33 consisted of Chinese, Taiwanese and Hongkongers, and the last 33 were Japanese.
The English names of K-Group and C-Group contestants are presented in Eastern order in accordance with the official website while J-Group contestants' names are presented in Western order.
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The Planet Top 9 was either selected by the mentors (Episode 2) or voted by viewers of the show; those selected to be the Planet Top 9 in Episode 2 were given the ability to reshuffle and organize cells.
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Planet Pass was a vote by the mentors, in which eliminated contestants could be brought back to the show.
The first two elimination rounds included a Planet Pass for one eliminated contestant from each group. The third elimination round included only one Planet Pass which could go to any eliminated contestant regardless of group. <div style="white-space:nowrap"> </div>
The first voting period took place from August 13, 2021, to August 28, 2021.
Voters (viewers and mentors) voted for three cells, as well as three girls of each group.
Eliminations were based on cell points, while the Planet Top 9 was based on individual points.
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Results from 1st Global vote where viewers chose 3 contestants each vote. Benefits are included.
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The second voting period took place from September 3, 2021, to September 18, 2021.
Voters voted for three contestants of each group.
Eliminations were based on individual points within K-Group, C-Group and J-Group.
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The third voting period took place from September 24, 2021, to October 9, 2021. Voters could only vote for one contestant from each group.
Eliminations were based on individual votes regardless of group. <div style="white-space:nowrap"> </div>
The first round of the fourth voting period took from October 15, 2021, until 10AM KST on October 22, 2021.
The second round was open during the finale live broadcast on October 22, 2021; all live votes were doubled.
Voters could only vote for one contestant out of the eighteen remaining.
The members of the debut lineup were decided based on individual votes regardless of group.
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The finale was held and broadcast live on October 22, 2021. Yeo Jin-goo announced the newly formed girl group name to be Kep1er ().
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Kep1er was supposed to debut on December 14, 2021, with the mini album First Impact, but due to one of their staff members testing positive for COVID-19, their debut was delayed to January 3, 2022. The group's debut performance at the 2021 Mnet Asian Music Awards on December 11 was also cancelled as a result, as well as some members testing positive for COVID-19. The group officially debuted on January 3, 2022. Since then, they have released two studio albums (one in Korean and one in Japanese), five EPs and three Japanese singles. In May 2024, it was revealed that all members, except for Kang Ye-seo (P06) and Sakamoto Mashiro (P08), renewed their contracts with WakeOne.