From left: ONF members Minkyun, E-Tion, Hyojin, Seungjun, U and Wyatt appear on the stage during the concert "Spotlight," held at the KBS Arena, Seoul, Sunday. (RBW, WM Entertainment)

ONF returned to the stage after a hiatus brought on by military service, presenting an energetic performance.

The six-member group performed a stand-alone concert, dubbed “Spotlight,” at the KBS Arena, Gangseo-gu, Seoul, on Saturday and Sunday.

Dressed in sparkling white suits, the group kicked off the concert with a series of charismatic songs including "New World," "Ugly Dance," and "Gucci," setting the tone for the concert.

"I've been waiting for this for so long. I'm so happy to finally be performing with the cheers we've been waiting for," said Hyojin, the group's leader.

Members reappeared on stage with casual and cute attire and approached closer to the fans. While singing "My Name Is," they held hands with fans and made eye contact.

Before singing "Love Effect," Minkyun asked the fans to sing along. "It's so heartwarming to hear you sing along to the chorus. It makes my heart swell." The fans, who had been cheering enthusiastically already, raised their voices even higher.

When some members of the group broke into tears during the performance, Wyatt briefly paused rapping. "I got emotional while performing because the lyrics are about how much I missed fans after being discharged from the military," said Wyatt.

The climax of the concert was the performance of the title track "Bye My Monster" from their new album "Beautiful Shadow," which was released Monday.

"Bye My Monster" is a pop dance track with a classic atmosphere and intense band sound, which references the theme of the third movement from Rachmaninoff's Symphony No. 2. "Out of all ONF songs released so far, 'Bye My Monster' is the best," said Hyojin.

The B-side track "Breath, Haze & Shadow" was also performed onstage. With a background filled with cherry blossoms, the members gently delivered a poignant ballad.

Having filled over 3 hours with 25 songs, the members thanked the fans and vowed to continue their activities.

"Thank you and sorry for making you wait for us during our military service. There were so many hardships, and there were moments when we even considered dropping everything, but we were able to come this far because of Fuse," Minkyun said, referring to the band's official fan club.

ONF performs during the concert entitled "Spotlight," held at the KBS Arena, Seoul, Sunday. (RBW, WM Entertainment)