Akdong Musician held a mini-concert on Friday in Seoul to mark the release of “Spring,” a new album full of the sibling duo’s trademark feel-good music and whimsical lyrics.

“We didn’t expect so many people to turn up, we’re truly moved,” said 17-year-old vocalist Lee Soo-hyun, referring to the swarms of families that filled the outdoor theater to hear the group perform at Seoul Forest on Friday, which was a public holiday and the day after Children’s Day.

Akdong Musician, which consists of 19-year-old songwriter Lee Chan-hyuk and his sister Lee Soo-hyun, dropped its new EP last Thursday, marking the duo’s return since its debut album “Play” in 2014.

“Spring” ranked No. 1 on the iTunes album charts in Hong Kong, Singapore, Taiwan and Thailand upon its release and has also been topping local music charts.

The main tracks are “Re-Bye,” a jazzy pop number on how easily people part ways, and “How People Move,” a funky track on the everyday movements of people.

“This album is more diverse in terms of musical color, and I did a lot of vocal training to adapt to the different sounds,” said Lee Soo-hyun. “For two years, I would go to the studio and practice singing just everything from R&B to rock, ballad and dance.”

The album additionally consists of the tracks “Haughty Girl,” “Green Window,” “Every Little Window” and “Around,” a ballad on the feeling of adolescent alienation.

“A lot of people are saying that this album doesn’t feel like our typical color and that we’ve become different,” said Lee Chan-hyuk. “But the truth is we actually finished this album a long time ago. It just took a long time to release because there are so many singers at our agency. ... We have many different sides to our music and this is just the beginning.”

The duo also plans to release an additional EP later this year.

By Rumy Doo (doo@heraldcorp.com)