Girls Planet 999

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.

Concept and format

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 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.

Promotion and broadcast

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," 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.

Cast

The series was presented by Yeo Jin-goo, dubbed as the "Planet Master." The rest of the mentors, also dubbed as "masters," were:

K-Pop Masters:
*Lee Sun-mi
*Tiffany Young
Dance Masters:
*Baek Koo-young
*Jang Juhee
Vocal Masters:
*Lim Han-byul
*Jo A-young
Rap Master :
*Woo Won-jae
Contestants

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.
;Color key

	Final members of Kep1er
	Contestants eliminated in the final episode
	Contestants eliminated in the third elimination round
	Contestants eliminated in the second elimination round
	Contestants eliminated in the first elimination round
	Contestants that left the show

Ranking

Planet Top 9

The Planet Top 9 was either selected by the mentors 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.
Color key:

	New Planet Top 9
	Returned to Planet Top 9

Planet Pass

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.

5	8	11
Ruan Ikema	Kotone Kamimoto	Guinn Myah
Wen Zhe	Zhou Xinyu	Guinn Myah
Kim Hyerim	Kim Suyeon	Guinn Myah

First voting period

The first voting period took place from August 13, 2021, to August 28, 2021.
Voters 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.
Color key:

Planet Top 9

Results from 1st Global vote where viewers chose 3 contestants each vote. Benefits are included.

Second voting period

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.
Color key:

	Planet Top 9
	Left the show

Third voting period

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.

Fourth voting period

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.

Result

The finale was held and broadcast live on October 22, 2021. Yeo Jin-goo announced the newly formed girl group name to be Kep1er.

Episodes

Discography

Extended plays

Singles

Ratings

Post-Competition

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, five EPs and three Japanese singles. In May 2024, it was revealed that all members, except for Kang Ye-seo and Sakamoto Mashiro, renewed their contracts with WakeOne.

Ye-seo and Mashiro left the group on July 15, 2024, after the group's concerts in Yokohama, Japan. They returned to their label 143 Entertainment and debuted in girl group Madein on September 3, 2024, with their first mini album, Rise.
Some contestants returned to their original groups:
*Ma Yuling and Wang Qiuru returned to SNH48.
*Liang Jiao and Liang Qiao returned to GNZ48.
*Su Ruiqi returned to Chic Chili.
*Wen Zhe returned to Hickey.
*Sim Seungeun returned to Bvndit and joined group promotions for their third mini album, Re-Original, in May 2022. Bvndit disbanded on November 11, 2022, after all the members terminated all their contracts with MNH.
*Lee Rayeon, Chiayi and Kim Doah returned to Fanatics. The group disbanded sometimes in 2024.
*Huh Jiwon, May and Kim Bora returned to Cherry Bullet and rejoined group promotions for their second mini album, Cherry Wish, in March 2022. Cherry Bullet disbanded on April 22, 2024, after several members, including Jiwon and May, terminated their exclusive contracts.
Some trainees left their agencies/joined new agencies:
*Chang Ching and Lee Yunji left Yuehua Entertainment and Cube Entertainment respectively. Later, they signed with FC ENM, the same agency of contestants Ririka Kishida and Hana Hayase.
*Ruan Ikema and Hina Terasaki signed with KISS Entertainment.
*Jeong Jiyoon signed with KM Entertainment.
*You Dayeon left Highline Entertainment.
*Han Dana signed a contract with Beats Entertainment.
*Miyu Ito signed a contract with 143 Entertainment, the company that manages Kep1er members Kang Yeseo and Mashiro Sakamoto.
*Li Yiman signed a contract with FLEX M.
*Shihona Sakamoto left Jellyfish Entertainment.
*Kim Yeeun left Fantagio Music.
*Choi Hyerin left MNH Entertainment.
*Chien Tzuling left Yuehua Entertainment.
*Kim Hyerim signed with Doubling Music.
*Xia Yan joined Real Show Culture Company.
*Lee Yeongyung joined Come & Funny Corporation.
*Risako Arai and Yume Murakami left Biscuit Entertainment. Then, Risako signed with iME Korea
* Kotone Kamimoto joined Modhaus.
*An Jeongmin left TOP Media.
*Sim Seungeun left MNH Entertainment.
*Hsu Nientzu left FNC Entertainment and joined Modhaus.
*SNH48's Wang Qiuru graduated on April 4, 2023.
*Zhou Xinyu left Yuehua Entertainment and joined Modhaus.
*Joung Min left Blockberry Creative.
*Choi Yeyoung and Ryu Sion left Blockberry Creative & joined Sure Space.
Some contestants debuted in new groups or debuted as soloists:
*Kim Suyeon debuted as a new member of Mystic Story's girl group, Billlie, under the stage name "Sheon". She debuted on November 27, 2021. She had her first release with the group on December 14 with their first digital single album The Collective Soul and Unconscious: Snowy Night.
*Su Ruiqi released her 8th digital single on December 14, 2021.
*Fu Yaning released her second digital single titled Starlight on December 27, 2021. She also starred in the iQiYi dramas My Heart and The Flowers Are Blooming.
*Ririka Kishida, Hana Hayase, Chang Ching and Lee Yunji debuted under FC Entertainment in a six-member group called ILY:1 on April 4, 2022. Lee Yunji and Chang Ching use the stage name "Ara" and "Rona" respectively while Ririka Kishida and Hana Hayase use their birth names.
*Shana Nonaka debuted in MLD Entertainment's new girl group, Lapillus, with the single "Hit Ya!" on June 20, 2022.
*Kim Hyerim debuted as a soloist on January 24, 2022.
*Yurina Kawaguchi debuted as a soloist on March 21, 2022, with her first single Look At Me.
*Kim Bora starred in the web-drama Jinx.
*Huh Jiwon starred in the web-drama Heart Way.
*Wen Zhe debuted as an actress.
*Yoon Jia debuted in Yes Im Entertainment group MiMiiRose on September 16, 2022.
*Miyu Ito debuted in 143 Entertainment's group LimeLight on February 14, 2023.
*Jeong Jiyoon joined Ichillin' and made her debut with the group on November 10, 2022.
*Ruan Ikema and Manami Nagai will debut in Kiss Entertainment's Japan-based girl group Kiss Girl's.
*Kotone Kamimoto, Hsu Nientzu, and Zhou Xinyu were revealed as TripleS' eleventh, thirteenth, and fifteenth member on January 2, March 20, and July 2, 2023, respectively.
*Momoko Okazaki joined Babymetal.
*Kim Doah debuted as a soloist on May 23, 2023, with the digital single "Dream Walking".
*An Jeongmin debuted as a soloist on June 24, 2023, with the digital single "Rainy Day", under the stage name JEOMi.
*You Dayeon debuted as a soloist on October 20, 2023, with the digital single "Down Down Down".
*Choi Yeyoung and Ryu Sion debuted in 5-member girl group Geenius, under Sure Space, on January 5, 2024.
*Guinn Myah debuted in TOP Media's new girl group Odd Youth on November 1, 2024.
*Risako Arai debuted in SW Entertainment's girl group UDTT, with the pre-debut single "Retry" on December 11, 2024. The group will officially debut on April 29, 2025.
*Nakamura Kyara debuted in Japan's based group BENNY, under TryCrew Entertainment, with the single "Woah", on February 21, 2025.
Some contestants participated in other survival shows:
*Moana Yamauchi participated in the Japanese survival show iCON Z.
*Zhou Xinyu, Cui Wenmeixiu, Gu Yizhou, and Cai Bing participated in the Chinese survival show, "Great Dance Crew".
*Lee Sunwoo participated in Channel A's "Youth Star".
*You Dayeon participated in Show Me the Money 11, but was eliminated in the first round.
*Sakurai Miu, Fujimoto Ayaka, and Kanno Miyu participated in Produce 101 Japan The Girls. Miu placed 4th in the finale and will debut as a member of ME:I.
*Lee Sunwoo and Choi Hyerin participated in Universe Ticket.
*Kim Bora and Huh Jiwon participated in Queendom Puzzle.
*Ikema Ruan, Aratake Rinka, and Kamikura Rei participated in Chuang Asia: Thailand. Ruan placed 2nd in the finale and will debut as a member of Gen1es.
*Hayashi Fuko participated in Mnet's I-Land 2: N/a in 2024.
*Moana Yamauchi participated in KBS's "The Entertainer".
*Fujimoto Ayaka and Oki Fuka participated in the Japanese audition show Black & White. Ayaka withdrew prior to the show's premiere due to visa procedures in South Korea, while Fuka ranked 8th and will debut in the "White" themed group MilMoon under VOLVE CREATIVE.