Billlie (빌리), formerly known as Mystic Rookies, is a 7-member girl group under Mystic Story Entertainment (a subsidiary label of SM Entertainment). The group consists of Moon Sua, Suhyeon, Haram, Tsuki, Sheon, Siyoon, and Haruna. They debuted on November 10, 2021 with the mini album, ‘the Billage of perception : chapter one‘. On May 17, 2023, the group made their Japanese debut.