Castle J

On December 22, 2019, Castle J appeared in the performance video released for the MCND pre-debut song "Top Gang", which was then released on January 2, 2020. On February 27, he then officially made his debut in MCND with the release of their debut mini album Into the Ice Age. In October 2021, Castle J, along with fellow member Win, participated in the Mnet reality show Show Me The Money 10.

Unfortunately, they were eliminated during the second round which was the 60 second beat rap. On May 31, 2022, Castle J released his first songs on SoundCloud in a playlist called "初年生".