BangChan/Christopher was apart of 3racha, a trío group under JYP Entertainment. It had him, Seo Changbin and Han Jisung. Bang chan wanted to create another group called 'Stray Kids' so JYP found trainees.

Bang Chan was going to be the leader and he had Changbin and Han Jisung already accepted into the group. There were candidates BangChan chose.

There was Lee Minho. He was doing amazing when he messed up a lyrical rap and JYP eliminated him.

Then there was Hwang Hyunjin, who did amazing with singing/rapping in Korean and dancing so he passed and was able to debut.

Then there was 17 year old, Lee Yongbok, another Australian like BangChan. Unfortunately, Yongbok struggled with Korean as he was still learning. BangChan could see how much he was trying. JYP eliminated Yongbok which left him in tears.

The last two Kim Seungmin and Yang Jeongin passed. BangChan walked off to the crying Yongbok and Minho who tried not to cry at the elimination. BangChan knew Minho was doing his best and he was able to teach Yongbok Korean.

BangChan went and talked with JYP to give the two he eliminated a chance. JYP eventually agreed but Lee Minho and Lee Yongbok needed to have stage names. BangChan thanked him then went to go tell everyone they passed and they were moving into a dorm the next day.