RM (BTS)
Rm took the longest time to train among the other BTS members. He trained at Big Hit Entertainment for 4 years. RM was supposed to be in a duo with rapper Iron but BTS was decided to be a group. Despite the changes and difficulties, RM still performed as the responsible leader of BTS.

Seulgi (Red Velvet)
Seulgi trained for a total of 7 years. She was training in the first year of middle school in 2007 when Girls' Generation debuted. She is talented in singing, dancing, and visuals.

G-Dragon (Big Bang)
The famous "King of K-Pop" spent a total of 11 years as a trainee. G-Dragon spent 5 years of training at SM Entertainment and the next 6 years at YG Entertainment. G-Dragon was supposed to debut as a duo with Taeyang, yet he debuted as the leader of BIG BANG.

Jihyo (TWICE)
Jihyo's training lasted for 10 years. She did not enjoy much of her childhood because she was only 8 years old when it started.  Taecyeon and Seulong were surprised that the child who used to run around is now the leader of TWICE.

Jennie (BLACKPINK)
Jennie trained for 6 years. She began training at YG Entertainment back in 2010. She was the first out of the members who would eventually make BLACKPINK.

S. Coups (SEVENTEEN)
S. Coup's training lasted for 6 years. He was the longest trainee among the other SEVENTEEN members. He belonged to the first male trainees of Pledis Entertainment. S. Coups is the leader of the Hip Hop Team.  

Johnny (NCT)
Johnny trained for a total of 9 years. Johnny came to SM Entertainment in 2008. He chose not to debut in the year 2012 because he was not ready. Johnny made his official debut as a member of NCT 127 in 2017.

Miyeon ((G)I-DLE)
Miyeon trained for 5 years at YG Entertainment. She joined YG Entertainment the same year as Jennie. She was slated to be a member of BLACKPINK. She left and joined Cube Entertainment where she made a debut in 2015.

Chaeryeong (ITZY)
Chaeryong became a competitor with her sister, on SIXTEEN, the survival shows that will assemble the members of TWICE. She made it to the end of the competition but she missed out on a place. She stayed as a trainee at JYP Entertainment. She did not quit and now she is one of the most successful rookies of 2019.