I.O.I title track 'Suddenly' hits No. 1 as Ju Gyeol-kyung shows up at Hong Kong reunion concert

I.O.I's title track Gapjagi ("Suddenly") reached No. 1 on music charts following the group's 10th-anniversary reunion comeback — their first activity since wrapping up in January 2017.

The nine-member lineup (Lim Na-young, Chungha, Kim Se-jeong, Jung Chae-yeon, Kim So-hye, Yoo Yeon-jung, Choi Yu-jung, Kim Do-yeon, Jeon So-mi) released mini album 3 I.O.I : LOOP as part of the reunion. Sources disagree on the exact release date: one outlet cites May 19 at 6 PM, another reports June 19. The group is currently working through an Asia tour that included a Seoul solo concert, 2026 I.O.I Concert Tour: LOOP in SEOUL, and has since moved to Hong Kong.

Two members — Ju Gyeol-kyung and Kang Mi-na — sat out the official comeback activities due to scheduling conflicts. Both showed up at the Hong Kong concert on June 23 to support the group in person. Ju Gyeol-kyung posted photos and videos from the venue on her SNS that day.

The post drew comments from active members. Jeon So-mi wrote "우리가 많이 좋아해" (we like you a lot); Lim Na-young replied "고마워 결경아" (thank you, Gyeol-kyung). (Choi Yu-jung also commented, telling Ju she loved her.)

Ju Gyeol-kyung debuted with I.O.I in 2016, re-debuted with PRISTIN, and has since focused on acting, primarily in China. I.O.I itself was formed through Mnet's Produce 101 audition program and ended activities in January 2017 after releasing hits including Neomoo Neomoo Neomoo, Gateun Gose-seo, Sonagi, and Beotkkochi Jimyeon.