From left, CNBLUE members Lee Jung-shin, Jung Yong-hwa and Kang Min-hyuk on the album cover for the band's new mini-album "X." Courtesy of FNC Entertainment

When CNBLUE debuted with the song "Loner" in January 2010, the band took the music scene by storm, making an enormous hit soon after its release.

About 15 years later, the group — vocalist Jung Yong-hwa, drummer Kang Min-hyuk and bassist Lee Jung-shin — is set for its 10th mini-album, "X," reflecting on the career they've built for over a decade.

The new album, which hit the shelves at 6 p.m. Monday, comprises six tracks the members took part in composing and writing lyrics: the lead single "A Sleepless Night," "BAD BAD," "RACER," "To. My Love," "Personal Color" and "Tonight."

The lead single, inspired by poet Ha Sang-wook's phrase, "Is it you that I miss, or is it that time?" is a medium-tempo rock song that portrays lingering memories of a former lover.

"X represents 10 for our 10th album, but it also signifies the infinite possibilities ahead of us. While it's an album that fully embraces the number 10, it also captures the infinite possibilities from our act and music we've built so far," Kang said in an interview with The Korea Times at the group's agency FNC Entertainment.

The group members said working on this album made them look back on their careers, which included forging a path in the rock band genre in the K-pop scene.

"In some ways, those who don't know us well often think we're a band that has had an easy path to success from the beginning. But from our perspective, we've been constantly working hard behind the scenes, really putting in a lot of effort to bring band music to the mainstream," Jung said.

"Now, occasionally I meet some musicians saying 'You made the guitar look cool, so I started learning it.' And those people are now in their 20s, playing in bands. So lately, I've been feeling that our efforts weren't in vain."

A photo for the group's new mini-album "X" / Courtesy of FNC Entertainment

Lee said he felt grateful for the group's fans.

"Many of the bands that were active when we debuted are gone. And I felt most grateful to our fans for allowing CNBLUE to continue making music and releasing albums, even if not frequently," he said.

"And I think I was most thankful to the members who were closest to me. I went through a preparation process where these feelings of gratitude really welled up inside me."

The new album is the first release in Korea in three years since they rolled out "WANTED" in 2021. The members shared that they went through a deep contemplation over their musical direction with the album.

"As we continued to ponder over musical aspects, there were inevitably some regrets and we wanted to do more. So naturally, the album's release was delayed. Even when we decided that we must create and release an album this year, we spent countless hours deliberating over various concerns and directions for it," Kang said.

And after a thoughtful process, the band decided to stay faithful to the basics.

"We've been preparing for three years, but suddenly, amid that, there has been a boom in the rock band genre starting last year. After much deliberation about our color, we ultimately thought about the song 'Loner.' Even now, I don't think it sounds outdated. And that's because it's fundamentally based on a raw band sound," Jung said.

"There were times when we used many musical sources or processed elements that were trendy at times until now. But this time, (we've decided) let's remove those and create sounds using only what guitars, drums and bass can produce naturally."

When asked about their personal lingering memories they miss, all three members recalled the times right after their debut.

"We were so busy then that we barely had time to sleep. It was very difficult. Just a few days after becoming a celebrity, we had this big hit 'Loner' and received a lot of love, but I don't have many memories of that time … For me, 2012 was the most nostalgic period," Lee said.