Sub-Unit Rainbow18 Brings Back Second-Generation K-Pop

Photo: Rainbow18 Instagram

2025 has seen a surprisingly long list of disbanded or inactive female K-Pop acts make their return. From the comeback of first-generation K-Pop group Baby V.O.X, the solo debuts of second-generation idols NANA from AFTER SCHOOL and Krystal from f(x), to the reunion of third-generation group GFRIEND, 2025 delivered for those missing past K-Pop eras. While not all these revivals happened as full-scale group comebacks, each musical act has their own way of re-entering the industry. In August, RAINBOW gained new music through the debut of Rainbow18, a sub-unit with main rapper Woori and main vocalist Hyunyoung. Rainbow18 debuted over a decade after the cute-themed Rainbow Pixie and the sexy-themed Rainbow Blaxx sub-units, which made their respective debuts in 2012 and 2014. 

FESTIVAL

Before this year, RAINBOW remained dormant in the K-Pop scene since reuniting for their tenth anniversary single album, Over the Rainbow, in 2019. However, on August 1, 2025, Woori and Hyunyoung brought back the group through the sub-unit Rainbow18. Through singer and entertainer Tak Jaehoon’s YouTube channel, they chronicled their sub-unit debut preparations online. Rainbow18 took inspiration for their sub-unit name from SISTAR19, a SISTAR sub-unit that made a comeback last year.

The duo eventually signed with K-TIGERS ENTERTAINMENT to release their debut EP, FESTIVAL. It included the dual title tracks “Festival” and “SNS (Slow N Steady),” a 2025 remake of Rainbow’s 2010 single, “A,” and the songs’ instrumentals. With “Festival” and “SNS (Slow N Steady)” primed for the summer with their dance-pop influence, it came as no surprise that they performed at Waterbomb Sokcho on August 23. 

“Good In Smile”

Released on November 25, the winter single “Good In Smile,” sees Woori and Hyunyoung connect more with the past through a collaboration with yewon, former member Jewelry. While Jewelry started as a group in 2001, yewon joined it during K-Pop’s second generation in 2011. After Jewelry’s disbandment in 2015, yewon last sang for “LOVE SIGN,” an OST she did in 2022 when she played the lead for the movie OH MY KISS.   

As Woori, Hyunyoung, and yewon’s active time as idols overlapped, this holiday song brings back a wave of nostalgia just from seeing the singers’ names together. The lyrics depict a wish for memories shared with loved ones during the holidays to feel “nearly timeless.”  Its instrumental comes with a city-pop vibe, like it emerged from the 1970s or 1980s. The video for “Good In Smile” captures a sentimental atmosphere with camcorder-like shots and polaroids and photo strips edited on top of footage.

Edited by Clark Royandoyan