Monday marked K-pop sensation BTS‘ ninth anniversary. And in celebration of the date, the septet took themselves to the stage to celebrate the release of its new anthology album, “Proof, ”and showcase live performances of its new songs.

The free-to-view live session was held online and streamed via the band’s official YouTube channel.

As the clock struck 9 p.m., more than 2 million Army members, the band‘s official fan group, flocked to the platform and filled the online chatting room with purple hearts, the group’s official color.

Donned in blue outfits, the seven bandmates -- Jin, J-Hope, Jimin, Jung-kook, RM, Suga and V -- appeared in order and sat down to jam inside the desert-themed stage. As they exchanged looks, BTS opened the event with a tune that fans have yearned for: “Born Singer,” a track from the first CD of the recent “Proof” album.

As the song reminisces about the first nine years of the band‘s journey since its debut in 2013, the different voices filled the open-air concert venue, and their harmony with the back chorus added more delight to the night.

The camera then panned to the sizzling sun, and the boys returned to the stage with a special guest: American singer-songwriter Anderson .Paak. Clad in his signature look -- black sunglasses and a Silk Sonic bowl haircut -- the musician slipped behind the drums for the band’s new chill-out R&B-themed track.

The night took a majestic turn as BTS performed “Yet To Come (The Most Beautiful Moment),” the lead single from their latest album. The energy from the song was palpable. “We‘re so happy to do this,” RM shouted as the melody came out, and the other members sang their way through the track by chanting the “moment is yet to come” section.

After the three-minute-long collaboration, BTS brought Anderson .Paak to center stage, where the seven members hugged the singer, thanked him for joining the live performance and asked him to talk about his first impression of the song.

“I love it. It reminds me of the church,” the American singer said before trying to talk to the group using a few Korean words.

“My son, Soul Rasheed, is a big fan of BTS and is the reason this performance came together. I’m obsessed. I‘ve been an Army member for a long time,” he added when RM asked how he decided to team up with the group.

After the second song, the band took the time to share what they thought was the “most beautiful moment” in their career.

J-Hope said the day BTS was born, June 13, was his best day without any hesitation. “I still get emotional thinking about it,” he added. For Jimin, it was the day BTS held its first concert in 2014, describing it as the “beginning of BTS’ best moments.”

“The day we held our first showcase at the Ilji Art Hall,” Suga said with a smile when asked when was his choice for the most beautiful moment. RM chimed in, saying the day BTS held a concert at the Olympic Gymnastic Arena was his favorite moment. V said it‘s sad that he can’t see Jung-kook cry again, saying it used to be a beautiful moment for him.

Jung-kook shared a heartwarming memory of his best moment: the day he joined then-Big Hit Entertainment. Jin said every single moment was a moment to cherish for him.

The 30-minute live session ended with “For Youth,” taken from their latest album. “It‘s a track dedicated to those who have been with us throughout our youth,” RM said as the bandmates appeared with mic stands.

As the group began singing their final song, the seven bandmates stretched their arms out to the camera while singing, “Would you give me your hand,” connecting themselves with Army members watching the live stream.

“Thank you!” the band shouted in unison as the song ended, bidding farewell to the first chapter of its nine-year career before embarking on the next step of its journey.

BTS dropped its anthology album “Proof” on Friday, unveiling three new songs with a three-disc album. The album sold more than 2 million copies on the day of its release, and “Yet To Come” landed at No. 3 on Spotify’s Global Spotify Daily Chart, with more than 7 million streams.