이달의 소녀 or LOOΠΔ is a South Korean girl group under BlockBerry Creative. 이달의 소녀 literally means "Girl of the Month", the name LOOΠΔ was obtained from all consonants of the group's name in hangul (ㅇㄷㅇㅅㄴ), arranged to become LOOΠΔ, while Loona (read as Luna) is a Latin name that means 'the moon'. As the name suggests, the group has 12 members that represent each month of the year.
A pre-debut project for LOOΠΔ started in October 2016. BlockBerry Creative released projects for LOOΠΔ every month, such as: reveal 'the Next Girl', release each member's music video & single album, fansign events, sub-unit projects, and other special events. The lead single to their debut album, 'favOriTe', was released in August 7, 2018. In August 19, 2018, LOOΠΔ held their debut concert 'LOONAbirth', followed by the release of their much-awaited debut title track 'Hi High' and their debut album [+ +] (pronounced 'plus plus') the following day.