Lee Si An originally appeared as a contestant on the survival show Idol School. She ranked 16th place in the finale, therefore being unable to debut with fromis_9.
2018–present: Produce 48
In June 2018, she became a contestant on the survival show Produce 48. She was eliminated in episode 11 after ranking 30th place.
In December 2019, a photo circulating from Banana Culture trainee Kim Nayoung's fan cafe showed her posing with Lee Si An in what appeared to be a girl group pre-debut photo. However, there has been no news regarding if Si An has switched to Banana Culture, if Nayoung switched to Stone Music, or if the image was photo shopped.