LIGHTSUM is not simply promoting in Japan. Five years after its Korean debut, the Cube Entertainment girl group has rebuilt itself as a Japanese-style idol act, moved the center of its activities to Japan, and is now following its Japanese debut album with a second local single in quick succession.
The scale of the shift was laid out in a November 2 SportsWorld column by pop culture critic Lee Moon-won, which argued that LIGHTSUM’s move should be read as a rebranding and a redebut rather than a standard overseas expansion. According to the column, the group released its Japanese debut album, ‘Re:idol,’ on September 23 through Warner Music Japan, more than five years after its Korean debut, and preceded it with a seven-part redebut documentary of the same name on the Japanese streaming platform ABEMA in August.
The concept changed with the market. SportsWorld reported that LIGHTSUM adopted the style of KAWAII LAB, the agency behind Japanese girl group CUTIE STREET, which had drawn attention in Korea earlier in the year. The Korea Times, reporting on the debut on October 1, described the same pivot in practical terms: the group overhauled its makeup, stage wardrobe and poses to foreground the bright, charming aesthetics of Japanese idols, and embraced local fan culture with individual fan-signing sessions, high-touch greeting events and one-on-one photo sessions. A Cube Entertainment official told the Hankook Ilbo, as cited by The Korea Times, that the group wanted to showcase Japanese idol culture together with LIGHTSUM’s new charms rather than target only a niche audience.
The results so far are modest but moving in the right direction. SportsWorld reported that ‘Re:idol’ placed No. 20 on the Oricon weekly album chart in its first week, while its daily album ranking climbed from a previous high of No. 11 to No. 4 three weeks after release. ChosunBiz reported on September 28 that the album had reached No. 11 on the Oricon daily album ranking at that point, with title track ‘Doshite’ at No. 3 on YouTube Japan’s daily chart, and that the group had performed at the SBI Music Circus festival in Hokkaido on September 26 and held a release event in Sapporo on September 27.
The next step comes fast. According to allkpop and ChosunBiz reports on October 31, LIGHTSUM will release the Japanese digital single ‘Merry Kiss’ on November 6, barely two months after ‘Re:idol.’ SBS reported on October 20 that the group will also hold its first Japan showcase, the ‘Re:idol SHOWCASE,’ at Spotify O-EAST in Tokyo on December 28. The group also released a Korean version of ‘Doshite’ on October 22 and performed it on Mnet’s ‘M Countdown’ as a full group for the first time in two years.
The reinvention follows a long stall at home. LIGHTSUM debuted in June 2021 with the single ‘Vanilla’ and released two mini-albums, two singles and one digital single through ‘POSE!’ in August 2024, SportsWorld reported. Its commercial peak in Korea remained modest: ‘Vanilla’ reached No. 531 on Melon’s daily chart with 18,357 listeners, still the group’s career high, while its second mini-album’s first-week sales of about 19,600 copies also stood as its best. After ‘POSE!,’ the group went quiet for roughly two years, and the lineup shrank from eight members to six: Sangah, Chowon, Nayoung, Hina, Juhyeon and Yujeong.
SportsWorld’s column traced part of the trouble to the pandemic era in which the group debuted, when the live-event market that smaller agencies rely on largely stopped working, and part to packaging, with a generic girlish concept and bubblegum pop that never gave the members a distinct identity. It also noted a detail that makes the Japan pivot less sudden than it looks: Nayoung, Chowon and Yujeong are all alumni of Mnet’s ‘Produce 48,’ and Nayoung and Yujeong were recruited from other agencies with a Japanese advance already in mind, since both had left strong impressions on Japanese viewers. The pandemic derailed that planned expansion, and weak Korean results eventually pushed the plan all the way to a full redebut.
Whether the gamble pays off is still an open question. The column itself flagged the obvious risk: the KAWAII LAB lane in Japan is already crowded, with FRUITS ZIPPER, CANDY TUNE and SWEET STEADY from the same stable plus rival groups working the same style, and non-major-agency acts typically need longer to establish themselves and turn a profit in the Japanese idol market. Its counterargument was that LIGHTSUM is not a pure copy, keeping its K-pop performance identity underneath the Japanese styling. For now, the test is simple and measurable: ‘Merry Kiss’ on November 6, the December showcase, and whether the daily chart climb continues into a durable local fanbase.
