Billlie is a seven-member South Korean girl group under Mystic Story. The members are MOON SUA, SUHYEON, HARAM, TSUKI, SHEON, SIYOON and HARUNA. The lineup includes five South Korean artists and two Japanese artists, TSUKI and HARUNA.

The group debuted on November 10, 2021, with the Billage of perception: chapter one and RING X RING. Initially a six-member team, Billlie expanded when SHEON joined later that month. Their December single snowy night introduced the complete seven-member lineup.

Billlie connects its songs, films and performances through an ongoing narrative. The name refers to an inner self or B-side that listeners can recognize in themselves. Their music explores contrasting moods through dance-pop, R&B and rock-influenced arrangements.

GingaMingaYo, RING ma Bell and EUNOIA represent different stages of that musical story. EUNOIA brought their first music-show win in April 2023. Their Japanese activities began with GingaMingaYo -Japanese ver.- in May 2023 and continued with the mini album Knock-on Effect in February 2024.

In 2025, MOON SUA and SIYOON introduced Billlie’s first official subunit with SNAP (feat. sokodomo). The group also took part in the international collaboration series KPOPPED.

Their first full-length album, the collective soul and unconscious: chapter two, arrived on May 6, 2026, following cloud palace ~ false awakening. ZAP and WORK anchor this chapter, while the Next Wave Award at the 33rd Hanteo Music Awards marked another group milestone.