Rookie girl group Billlie participated in 1theK's 'Switch On' series. 

Members of Billlie revealed a vocal cover of four-hit songs. The group which will soon debut under Mystic Story taken a creative approach to the task and changed the style of songs.

Here is the full playlist with timestamps and descriptions:

0:00 aespa 'Next Level'

0:25 aespa 'Next Level' (Acoustic ver.)

1:07 TWICE 'Alcohol-Free'

1:47 TWICE 'Alcohol-Free' (Citypop ver.)

2:31 BLACKPINK 'DDU-DU DDU-DU'

3:07 BLACKPINK 'DDU-DU DDU-DU' (Ballad ver.)

3:53 BTS 'Permission To Dance'

4:25 BTS 'Permission To Dance' (Band ver.)