The first wave began in October 2016, debuting HeeJin, HyunJin, HaSeul, YeoJin, and Hong Kong native Vivi (the sole non-Korean member). All but youngest member YeoJin would join to form Loona's first subunit, Loona 1/3. The foursome issued their first EP, the Korean Top Ten debut Love & Live, in March 2017, with a repackaged version, Love & Evil, landing a month later.
The second wave of singles kicked off soon after with previously announced member Vivi, as well as Kim Lip, JinSoul, and Choerry, who formed the subunit trio Loona Odd Eye Circle. Their EP, Mix & Match, was released that September, with the Max & Match repackage pushed out the next month. While these short-plays marked a slight slide down the Korean charts, they also started Loona's ascent on the U.S. charts.
The third and final wave -- which resulted in subunit Loona yyxy -- extended from late 2017 into 2018. In addition to Yves and Go Won, Loona yyxy also included Chuu and Olivia Hye, whose high-energy beats and cool synth styles helped push their individual singles to the highest chart placements of any Loona member. The subunit's EP fared just as well, as Beauty & the Beat -- which featured an appearance by Grimes on "love4eva" -- peaked at number four in Korea and number six on the U.S. World Albums chart upon release that May.
Almost two years after the group's emergence, the 12-piece finally convened to issue their official debut EP, + +, in August 2018. Featuring the single "Favorite," + + rose to number two in Korea and peaked at number four on the U.S. World Albums and Heatseekers charts. ~ Neil Z. Yeung, Rovi