In the first half of 2026, a 'Back to 2010' trend is sweeping the K-pop industry as second and third-generation idol groups announce reunions and complete lineup activities. I.O.I, known as 'the first girl group selected by national producers,' made a surprise reunion announcement on June 25 to commemorate their 10th debut anniversary. Out of 11 total members, 9 members, excluding Joo Kyul-kyung and Kang Mi-na, participated in the reunion. Since their disbandment, members had been developing their individual talents across variety shows and acting. The members showed exceptionally strong determination for this reunion, directly proposing the idea to their agencies. Swing Entertainment, their former management company, coordinated schedules among the 9 members' current agencies to make the reunion possible. The reunited I.O.I demonstrated their continued influence, achieving #1 on music charts and music broadcast rankings with their new song 'Suddenly.'