"It's like I'm surfing for the first time and a big wave just came through," she says.

"And I'm trying my best to get through it."

In the film, Golden is performed in the film by girl band HUNTR/X, consisting of Rumi, Mira and Zoey.

According to the Official Charts Company, it's the first K-pop single to top the UK chart since PSY's Gangnam Style in 2012.

Ejae, who provides the singing voice of Rumi, performs some of the soundtrack's songs and also co-wrote Your Idol, How It's Done and the Hunter's Mantra.

She tells Newsbeat ending up on the final recordings was an "organic process".

"I've been singing all the demos while writing the songs," she says.

"I guess we got used to me singing it. And they were like: 'Hey, do you want to sing?'

"I was just like: 'Why not?'"

Ejae says the outpouring of support has been "overwhelming".

She gained almost 100,000 Instagram followers in a month and says she's been getting used to the spotlight instead of "working behind the scenes".

The KPop Demon Hunters crew knew Golden was a "banger" when they wrote it, she says, but had no idea how huge it would become.

But Ejae has an idea as to why the song has captured so many fans.

"I think we're in a time right now where we need hope and people are wanting that," she says.

"And this song is very hopeful, it just lifts your voice and it's a very powerful song.

"I think maybe that's what people need right now."

HUNTR/X face off against demon boyband the Saja Boys in the movie - and their single Your Idol climbed to number 10 in this week's chart.

The Official Charts Company's editor Carl Smith tells Newsbeat it's a "sign of how popular K-pop is right now".

He says both songs are "amazing pop songs with great melodies" and the film allows fans to "visualise their new favourite band".

The last time an animated film soundtrack reached number one was when single We Don't Talk About Bruno, from Disney's Encanto, held the top spot for seven weeks in early 2022.

Carl thinks Golden could have similar staying power.

"It could possibly be the song of the summer," he says.

"I think its popularity transcends generations."

Katy, who runs K-pop site Hallyu Doing, tells Newsbeat the success of KPop Demon Hunters is exciting for UK fans.

"I'm seeing people who are not K-pop fans that have seen the movie and are now looking into K-pop artists for real that they want to go and see," she says.

Elsewhere in the charts, Drake and Central Cee scored the week's highest new entry with their collab Which One landing at number four.

And music from Ozzy Osbourne, whose funeral was held in Birmingham this week, continued to climb the charts after his death.

Black Sabbath's Paranoid climbed 12 places to the top 20, while Ozzy's solo track Crazy Train hit number 25 - its highest-ever position in the UK.