Ksoul (소울) was born as Liu Zekai (刘泽闿) on October 19, 2000 in Chengdu, China. He participated in My Teenage Boy/Fantasy Boys with a final rank of 9th; making him a member of the boy group FANTASY BOYS, under PocketDol Studios.
Ksoul made his official debut in China on 2018 as a member of the boy group Mu Ji Shao Nian, using the stage name Su Er. He later changed his legal name to Su Er (苏尔).
He has been on an on-and-off hiatus since September of 2023 due to the deteriorating health of his father and grandmother. It was announced in early March that his father has passed away on February 25th.