On May 29, Kim Sejeong uploaded screenshots of the Melon TOP 100 chart to her Instagram account, proudly revealing that I.O.I’s latest title track Suddenly had officially climbed to No.1.

The achievement marks a particularly meaningful moment for the project girl group, who reunited this year to celebrate the 10th anniversary of their debut.

Alongside the chart screenshot, Kim Sejeong posted a heartfelt message directed toward fellow member Jeon Somi.

“You became Jeon Somi. Suddenly! You’re the center now!” she jokingly wrote, referencing Somi’s famous center position during I.O.I’s original promotions.

Kim Sejeong continued emotionally, saying: “Something like this happening on the day of the concert feels like a drama writer couldn’t even script it this perfectly. From the very first moment I met you until now, every single moment has felt unbelievable.”

The singer and actress also reflected on the memories shared between I.O.I and their fans throughout the past decade.

“I think the best way to hold onto time that passes too quickly is by creating as many memories as possible,” she shared. “I’m so thankful and happy that our songs, our teenage years, our twenties, and our dreams were able to connect with your memories too.”

She added: “You know that you can never forget the people you shared memories with for the rest of your life.”

Kim Sejeong also opened up about the emotional struggles that often come with chasing dreams, writing that dreams can sometimes collapse despite hard work and that achieving them often requires enduring loneliness and difficult periods for a long time.

“Thank you for making this dream and this name come true,” she told fans, while also expressing hope that their own dreams would one day come true as well.

She concluded the post with a touching message: “Thank you for still calling our name and for never letting go.”

I.O.I — consisting of Lim Na-young, Chungha, Kim Sejeong, Jung Chae-yeon, Kim So-hye, Yoo Yeon-jung, Choi Yoo-jung, Kim Do-yeon, and Jeon Somi — made their highly anticipated return on May 19 with their third mini album I.O.I : LOOP.

Their reunion title track Suddenly has continued gaining momentum since release, steadily climbing domestic music charts before eventually reaching the top of Melon’s TOP 100 ranking.

After successfully wrapping up music show promotions, the group is now meeting fans through their three-day concert event, 2026 I.O.I Concert Tour: LOOP, taking place from May 29 to May 31 at Jamsil Indoor Stadium in Seoul.

Sources: Daum | 뉴스엔