In the fast changing K-pop industry, BoA has stood the test of time.

Including her latest EP “Starry Night” in December and her debut at age 13 with “ID; Peace B” in 2000, she has sold millions of records and become a household name in South Korea.

And then there was “No. 1.” Around two years into her career, she released her second studio album with the track on her home turf after her million-seller Japanese debut album “Listen to My Heart” topped the Oricon chart.

It was a perfect homecoming that propelled her to nationwide stardom, at a time when the Seoul-Tokyo relations were improving as the 2002 World Cup took place in both countries in the same year.

“‘No.1’ is a song that gifted me with the most meaningful and happiest moment of my career so far,” BoA told The Korea Herald.

With the song, she became the youngest to win the grand prize of SBS Gayo Daejeon, a music awards show that aired on SBS until 2016 which has now become an annual televised music show.

“I often sing ‘No. 1’ as the last song at my shows, which is met with the loudest screams from my fans. It’s a fan favorite,” she added.

Norwegian songwriter and producer Sigurd Rosnes, who goes by “Ziggy,” recalls the time he made the song nearly two decades ago when the capital-P pop sound, spearheaded by the likes of Britney Spears, dominated the world.

“I’d programmed the drums and I knew that I wanted to write kind of an uplifting happy thing – something that would make you feel good,” Rosnes said.

Though he normally sings gibberish to fill in the melody, this time he had already come up with the phrase “You’re still my number one” -- the famous line for the chorus that many Koreans can still sing along off by heart.

“This was when Max Martin started out doing his stuff with Britney. Not the chorus, but I felt like the verse had a similar vibe to it,” he explained.

Originally, “No. 1” was not the lead track, according to Jason Park, a former S.M. Entertainment employee who worked at the overseas business team at the time. Rather, it was just one of many tracks on “hundreds of demo CDs” that ended up in the hands of her label before gaining favorability from staff and later executive producer Lee Soo-man, who was very much into Max Martin at that time.

The lead single was originally slated to be a song by the label’s in-house composer Yoo Young-jin, which meant that someone had to buck the hierarchy to clear the spot for what would become one of BoA’s biggest hits.

“I was also working as producer Lee’s driver at that time and got a chance to play the song in the car, explaining to him that this song from our business trip to Sweden was a better choice,” Park said.

BoA’s second studio album “No. 1” went on to sell over 500,000 copies, becoming one of the best-selling records of the year in Korea, according to the Recording Industry Association of Korea.

Music critic Lim Jin-mo believes her success in Japan in the early 2000s, when it was an unlikely achievement for a South Korean act, opened many doors for pop acts from her country in the second largest music market in the world before the K-pop industry turned its attention to the US.

“BoA acted as a figurehead for breakthroughs in Japan for South Korean acts, a country with a bigger and more developed music industry, becoming a pivotal figure in K-pop’s history,” he said.

Tamar Herman, a K-pop correspondent for Billboard, agrees.

“As a result, the Japanese music market became more familiar with Korean artistry and a major market for just about every other K-pop act that followed.”

As fate would have it, BoA released “Only One” in 2012, her seventh Korean language studio album with a self-written lead single of the same title.

The melodious mid-tempo track was a departure from her signature dance-pop persona, but like “No. 1,” it wasn’t initially intended to front an album until executive producer Lee Soo-man had a change of heart.

And through songs like ‘CAMO’ and ‘Woman’ in her recent years, BoA has continued to reinvent herself, as well getting more involved in the creative process.

“Two decades in, and her most recent releases show a whole new side to her than she’s ever depicted before, putting both her identity as an individual, not just a pop star and as a woman in the spotlight,” Herman added.

By Yim Hyun-su (hyunsu@heraldcorp.com)