Regarded as the “Retro Queens” of K-Pop, members of Wonder Girls have released a diverse range of solo projects when they were part of the group, after they left, and following the group’s disbandment. Let’s take a look at some of the best B-sides released by Sunmi, Yubin, HA:TFELT aka Yeeun, Hyerim aka Lim, and HyunA. Members Sunye and Sohee aren’t included since the two focused more on their acting careers to become successful actresses.

“Black Pearl” by Sunmi

Written solely by Sunmi, “Black Pearl” appeared on the songstress’s second mini-album WARNING. The track is a jazzy R&B song featuring a sexy saxophone in the post-chorus. With lyrics referring to the process of pearl making, Sunmi presents a cynical take on how we live our lives as a pearl, nurturing ourselves hidden away from the world.

“Game Over” by Yubin

“Game Over” is an urban hip-hop song written and composed by Yubin, and appears on Yubin’s single album #TUSM. Layered on top of a retro rhythm, Yubin's unique voice harmonizes with a groovy melody. The lyrics share an emotional message that even if the love game between her and her lover doesn’t have a happy ending, she doesn’t care. 

“Iron Girl” by HA:TFELT ft. Hyerim

A collaboration between the two Wonder Girls members, “Iron Girl” was the intro to HA:TFELT’s 2014 mini-album Me?. The album was included in Billboard's list “10 Best K-Pop Albums of 2014.” “Iron Girl” is a mid-tempo song with gritty instrumentation, with the two singing an autobiographical tale of how they may not be bright shining golden girls, but they are strong iron girls.

“Green Apple” by HyunA ft. Jung Ilhoon

Released after HyunA’s appearance in PSY’s global viral hit “Gangnam Style,” HyunA’s mini-album Melting is an underrated collection of pop gems. “Green Apple,” also known as “Unripe Apple,” appeared on the mini-album and is a collaboration with Jung Ilhoon, formerly of BTOB. The track is a bubbly teen-pop song with cute lyrics about having a crush and trying to make a good first impression.