18th Letter – 내 잘못이야
Track 01 from Single "내 잘못이야 (Feat. J.breath(제이브리스))"
Release Date: 2018.12.19
18th Letter – 알바끝나고 집에 간다며 (Vocal by 한규리)
Track 01 from Single "알바끝나고 집에 간다며"
Release Date: 2019.01.18
18th Letter – 비교하게 돼
Track 01 from Single "비교하게 돼"
Release Date: 2019.05.18
18th Letter – 첫 연애, 첫 이별
Track 01 from Single "첫 연애, 첫 이별"
Release Date: 2018.01.29
18th Letter – 언제나 우리둘 (Vocal 황비)
Track 01 from Single "언제나 우리둘"
Release Date: 2018.04.18
18th Letter – 잊을게 (Vocal. J.breath & 황비)
Track 01 from Single "잊을게"
Release Date: 2018.06.18
18th Letter – 넌 별 (duet by 무성,한규리)
Track 01 from Single "넌 별"
Release Date: 2018.10.11