Siblings can be a pain, especially if you have to work together. For K-pop’s one-and-only sibling duo AKMU, each was the source of the other’s pain — but also the reason they could carry on.

But “the longer we kept on going as AKMU, the harder it became for me to change my style to the one that my brother wanted,” Lee Su-hyun, the sister in the duo, told reporters on Monday.

“So this time, I made him promise we would do the kind of music I wanted. I declared I would not try anything new after ‘Nakka’ [2021] and told him I did not want any new challenges. I wanted to go back to 10 years ago when we sang lighter songs that made me feel good like ‘200%’ [2014].”

So came “Love Lee,” the duo’s fourth and latest single and its first in two years since “Next Episode” was released in July 2021. “Next Episode” was a “collaboration album” in which the duo invited different artists for all of the seven tracks, including “Nakka” with IU, in the compilation.

For “Love Lee,” the siblings have returned to the playful and witty vibe they were known for when they first took Korean pop music by storm on SBS’s audition program “K-pop Star 2” (2012-3). “Love Lee” is a wordplay of the words lovely and love for the two Lees — siblings and AKMU members Lee Chan-hyuk and Lee Su-hyun, according to the duo.

As always, the title track and the B-side track “Fry’s Dream” were written and lyricized by Chan-hyuk, while his younger sister completed it with her unique, velvety vocals.

AKMU is one of the most unique artists in Korea. Both siblings are talented in music but in different ways — the brother, born in 1996, a genius songwriter and the sister, born in 1999, a singer with an angelic voice — have been working together without friction for over a decade.

“Working with your sister means that the waiting room feels like home,” Lee Chan-hyuk said.

“There are the subtle conveniences that minimize our stress and I have been feeling that more and more as the years roll by. The ability to relax in the waiting room means that we can recharge more than any other group.”

The duo joined YG Entertainment after winning the audition program and have been known for multiple hit tracks — most of which were written and produced by the duo — such as “Give Love” (2014), "RE-BYE" (2016), "Last Goodbye" (2017) and more, since its debut in 2014.

Ever since "Dinosaur" (2017), however, the band had been knocking on the more experimental side of pop music in a move led by Chan-hyuk. But after releasing his solo album last year, he realized he could pursue his dreams with his own name and not the duo’s.

“I watched Su-hyun truly enjoying herself more than ever while working on ‘Love Lee,’ and I realized how much I had been pushing for the music style that only I wanted,” Chan-hyuk said.

“Since ‘Dinosaur,’ she found it harder to sing and fully engage with the music. It actually took me a long time to notice it, but I felt she was not enjoying the music as much as before. Working on ‘Love Lee,’ I realized that AKMU is a team effort requiring us to work together.”

The duo added another fun twist for Monday's press showcase by preparing a radio session with the reporters. Attendants were asked to share fun anecdotes without revealing their names, which were read out and commented on by AKMU, who turned into the radio DJs for the day.

In one episode, a reporter shared that they also had a little sister but felt like they were drifting away from each other, while another reporter was worried whether it was OK for them to spend time on their own without a lover.

“For families, and any relationship actually, it’s easy to take people for granted,” Chan-hyuk said in response to the first episode. “I used to take it for granted that I could take Su-hyun’s voice like a toy and make her sing whatever I wanted her to. But I realized that it takes both of us to accomplish this job. I think with people you’re close to, it’s important to tell them you love them even if you feel like you don’t have to.”

Su-hyun’s brother was actually the reason she felt so frustrated that two years ago, she considered quitting and leaving the industry. But he was the one who told her not to give up and helped her rediscover her love for music.

“To be frank, I’m still recovering from the slump,” she said. “But my brother kept giving me advice and told me that he wanted me to find something that I can enjoy. So rather than waiting for myself to make a full recovery, I wanted to come back while someone was beside me and cheering me on. I hope this album will give me the positive energy that I needed.”

The radio session was prepared so that she could reveal herself more candidly in a setting that felt more comfortable than a formal press conference.

“Back then [10 years ago], we didn’t know why fans loved us — we were confident for no reason,” Chan-hyuk said. “But now, we know what we’re good at and what people want. ‘Love Lee’ is similar to ‘200%’ but I think we’ve become more professional and mature.”

The band celebrates the 10th anniversary of its debut in April 2024. “Love Lee” is the first step in a series of projects the duo is working on for the celebratory year.

“We’ll also hold a concert for the first time in three years,” Chan-hyuk said. “We’re very much looking forward to it, so we hope you do as well.”

BY YOON SO-YEON [yoon.soyeon@joongang.co.kr]