[2] Prior to their debut, the group promoted with Chaeyeon, Jisoo, Hyungseo, Minji, and Soyeon.

[7][8] They released their first extended play Pinky Promise on July 31, 2019, marking the official debut of member Yeseo.

[12] On March 29, Hyungseo posted a letter to the official fan cafe announcing her departure due to her wanting to focus on her studies.

[13] Chaeyeon didn't participate in the comeback due to conflicting schedules caused by her MC position in Boni Hani.

[16] On October 22, 2021, new member Yunji performed with Busters for the first time during a concert at Jeongdong Theater.