[5] With the addition of Daeil and Byungho, 24K released their first mini album Hurry Up and the title song on September 6.

[6] On January 16 of the following year, 24K began an additional promotion cycle for the record by performing "Secret Love.

[8] A "cute" concept, the title track features a "hard rock guitar sound" mixed with a "European-style house beat.

[11] On October 1, 2015, 24K made a comeback with their third mini album Super Fly and the title track of the same name.

[12] 24K had their first European concert in Warsaw, Poland on January 23, 2016, at Progresja Music Zone Main Stage, without Sung-oh.

They held a showcase in Malaysia from April 22 to 24 which was presented by New Pro Star, with Sungoh and Daeil being absent for unknown reasons.

The blacklist's existence was made known in October 2016 before the president's impeachment, the full list being uncovered in April.

On June 26, 2019, the company announced that Jinhong was not renewing his contract, Hongseob would not be able to continue for health reasons, and Jeonguk has chosen to concentrate on his solo work.

On February 15, 2023, the group participated in survival show, Peak Time, as Team 21:00, without Changsun, but were eliminated and revealed in the seventh episode.

On September 25, 2023, Changsun officially left the group and Choeun Entertainment in a handwritten letter posted on his Instagram account to focus on his activities in TAN.

The song also holds songwriting credits for members Imchan and Xiwoo, as well as two new tracks, "Shooting Star" and "Seraphic".

[23] On the second EP U R So Cute, the group incorporated elements of hip hop and electronic dance music into its sound.