LOONA 1/3 (이달의 소녀 1/3; stylized as LOOΠΔ 1/3) is the first sub-unit of the girl group LOONA. The sub-unit was initially comprised of ViVi, HaSeul, HeeJin and HyunJin. They debuted on March 12, 2017, with the mini album Love & Live.[1]
On October 27, 2017, YeoJin revealed through the 200th episode of LOONA TV that she represents the “slash” in 1/3.[2]