Nine years ago, eleven trainees walked off the stage of Mnet’s Produce 101 as Korea’s first viewer-built girl group. They had eleven months together, two studio mini-albums, one mega-hit (“Very Very Very”), and a contractually-mandated breakup in January 2017 that sent everyone back to their home agencies. That, fans assumed, was that.
Then, on May 19, 2026, the impossible quietly happened. I.O.I (아이오아이) returned — nine of the original eleven members reunited under Swing Entertainment, dropped their third mini-album I.O.I: LOOP, and immediately watched the title track “갑자기 (Suddenly)” rocket to #3 on Melon’s Hot 100 and #4 on the Top 100. The reunion concert tour opens tonight (May 29, 2026) at Seoul’s Jamsil Indoor Stadium for a three-night run, followed by an Asia leg.
For Korean fans who voted these eleven into existence as “국민 프로듀서 (national producers)” a decade ago, the headline writes itself: the experiment worked. Here’s the full story of the comeback that nobody expected to actually arrive.
Who I.O.I are, and why “national girl group” stuck
I.O.I (an abbreviation of Ideal Of Idol) was the first project group built by Mnet’s Produce 101 in 2016. The show’s gimmick: 101 trainees from dozens of agencies competed across 11 episodes, with viewers (“national producers”) voting the final 11 into a temporary group with a fixed expiration date.
The original lineup that debuted on May 4, 2016 with “Dream Girls”:
- Lim Na-young (임나영) — went on to Pristin, now solo
- Chung Ha (김청하) — became one of K-pop’s most respected solo artists
- Kim Se-jeong (김세정) — Gugudan, then a top-tier actress (School 2017, The Uncanny Counter, Business Proposal)
- Jung Chae-yeon (정채연) — DIA, and a working actress
- Kim So-hye (김소혜) — pivoted entirely into acting
- Yoo Yeon-jung (유연정) — Cosmic Girls / WJSN
- Choi Yoo-jung (최유정) — Weki Meki
- Kim Do-yeon (김도연) — Weki Meki, and acting
- Jeon Somi (전소미) — now a global solo star under THEBLACKLABEL
- Kang Mi-na (강미나) — Gugudan, then acting (not participating in 2026 reunion)
- Zhou Jieqiong / Pinky (주결경) — Pristin, then Chinese solo activities (not participating in 2026 reunion)
By the time the group disbanded on January 29, 2017, they’d dropped two mini-albums (Chrysalis, Miss Me?), the JYP-penned megahit “Very Very Very (너무너무너무),” and a farewell single (“Downpour”). Nine months of activity. Eleven million-selling national-producer-voted memories.
Why a 2026 reunion — and why now
The official story is that this is a 10th-anniversary project. The behind-the-scenes story, per multiple Korean entertainment reports, is that Chung Ha quietly led the reunion call — reaching out to former members individually, coordinating schedules across about a half-dozen different agencies, and convincing Swing Entertainment to anchor the comeback.
Two of the original eleven — Kang Mi-na and Zhou Jieqiong — couldn’t participate due to existing scheduling conflicts. The other nine were in. Practice-room photos started leaking in early May 2026, and a reunion poster dropped on April 29 confirming the May 19 release.
The album: I.O.I: LOOP and “Suddenly”
The mini-album dropped on May 19, 2026 at 6:00 PM KST — the group’s first new release in roughly nine years. The title track “갑자기 (Suddenly)” is a synth-pop song built around nostalgia and reunion as a theme; Jeon Somi co-wrote the lyrics. The chart performance has been everything Swing Entertainment hoped for:
- Melon Top 100: #4 (as of May 26, 14:00 KST)
- Melon Hot 100: #3
- YouTube Worldwide: “Suddenly” MV trended at #1 globally on release day
For a group that hadn’t released a song in nine years, those numbers are not nostalgia — they’re a working hit.
Watch the “Suddenly” MV
The MV leans into the reunion theme: melancholy synth-pop, dreamy color grading, the nine members back on screen together in a way many fans had genuinely stopped believing would happen.
Video: 아이오아이 (I.O.I) ‘갑자기 (Suddenly)’ Official MV — Swing Entertainment / YouTube.
“It feels like a dream. To all the national producers, our 앙둥이 (fans), and everyone who listened — thank you, truly. We’ve achieved so many things again with I.O.I.”
— I.O.I members, on social media after the release
The concert: 2026 I.O.I Concert Tour LOOP
The tour opens tonight:
- Seoul: May 29–31, 2026 — Jamsil Indoor Stadium (잠실실내체육관) — 3 nights, sold out
- Bangkok: upcoming — venue TBA
- Hong Kong: upcoming — venue TBA
- Additional Asian cities to follow
Members have already done full-live performances on Korean music shows since the comeback — no backing tracks, all nine on-stage harmonies — and the response has been emphatic. Even the typically harsh Korean online commentariat is mostly leaving comments like “그 시절 국프들 멤버 진짜 잘 뽑았다” (“the national producers really picked the right members back then”) and “매년 한 번씩 모여서 컴백해주면 안되나” (“can they just regroup once a year, every year?”).
Where each member is now (the post-I.O.I careers)
What makes this reunion land harder than most nostalgia projects is the individual track record. In the nine years since I.O.I dissolved, the members’ solo careers have collectively become one of K-pop’s deeper benches:
- Chung Ha — one of the most respected vocalist-dancers in solo K-pop
- Kim Se-jeong — broke out as a leading actress (Business Proposal, The Uncanny Counter)
- Jeon Somi — global solo star with THEBLACKLABEL (sister label of YG), with the kind of crossover Western reach few Korean soloists have
- Kim Do-yeon, Choi Yoo-jung — anchored Weki Meki and built individual acting/variety careers
- Yoo Yeon-jung — Cosmic Girls / WJSN frontline vocalist
- Jung Chae-yeon, Kim So-hye — moved into acting full-time
- Lim Na-young — returned to solo work after Pristin
When this many people with this much individual success voluntarily clear a quarter of a year to come back together, it’s not nostalgia. It’s deliberate.
Why this reunion is bigger than the nostalgia angle
“Project group reunions” are usually safe nostalgia plays — one show, one song, fan service. I.O.I’s 2026 comeback is something else: a full mini-album, a multi-city Asia tour, sustained variety appearances (the group taped Knowing Bros in May), top-3 chart performance, and a #1 worldwide YouTube trending slot on release day.
The Korean industry is paying attention. So is everyone who voted on Produce 101 in 2016 — now nine years older, still texting each other to remember to vote on Melon. Tonight in Jamsil, that vote becomes a stadium.
Sources:
SPOTV NEWS — 아이오아이, 9년 기다린 보람 있네…건재함 증명한 ‘국민 걸그룹’ (2026.05.28) ·
Wikipedia — I.O.I ·
Korea Herald — I.O.I to reunite in spring 2026 for 10th anniversary ·
Allkpop — I.O.I reunites in practice room for 10th anniversary ·
Koreaboo — Long-awaited I.O.I comeback confirmed for May ·
네이트 연예 — 아이오아이, 드디어 재결합 (2026.05.19) ·
YouTube — I.O.I ‘갑자기 (Suddenly)’ Official MV (Swing Entertainment)
