“I didn’t want it to veer into the romance genre of, like, oh, this woman meets her K-pop idol and there’s some kind of traditional romance between the two of them,” she says. “I thought that was super boring and cliché, so I was like, I don’t want to go near that.”

Sure, there are popular stories that employ that trope – such as the film The Idea of You, in which Anne Hathaway and a boy band singer meet and fall for each other at California’s Coachella music festival. But that kind of story held no appeal, Ma-Kellams says.

“I wanted to write something much more ambiguous I haven’t seen before,” she says, “where the relationship is not even classifiable. Because I think those are the most interesting kinds of narratives, where you don’t quite know, like, Is this romantic? Is this maternal? Is this like a weird combination of the two?

“I think that makes for the most narrative tension for me as a reader, where, like, I don’t know. The situation shifts so I don’t know where it’s going, if it’s going to be intimate and physical or stay in the purely psychological or interpersonal connection.”

In The Band, the K-pop star, Sang Duri, has unintentionally angered the fandom of The Band – that is his group’s name – with a lyric from a solo single. He decides to disappear in Southern California to take the heat off his four Band mates, and comes upon the professor as she is perusing the frozen tteokbokki rice cakes in an H Mart near her South Bay home.

The professor, whose given name is only mentioned once in the book, invites him home, to the suspicions of her husband and confusion of her two young sons.

Duri ends up staying as the rest of The Band also come to the United States to appear on a daytime talk show, a late-night sketch comedy show, and eventually a music awards show at the explosive climax of the story.

Ma-Kellams is a psychology professor at San Jose State University, alternating semesters between remote classes from her home in Torrance, California and in-person courses in San Jose.

“I was very late to the game,” she says. “But then once I discovered them, I realised that this was an entirely different phenomenon than the NSYNC or Backstreet Boys fandoms I had known about many years ago.”

The BTS Army, as its fandom is known, particularly fascinated her with its intense support of the members of that group.

“I thought it’d be really interesting to write a story about this,” Ma-Kellams says. “Not only this phenomenon centred on K-pop and the kind of relationships with the fandom. I thought it would be interesting to have it in the US to have a sort of cross-cultural element.”

Ma-Kellams spent days on YouTube catching up on the rise of K-pop over the previous decade. Global superstars BTS became the closest model for The Band she created in the book, but the lives and careers of other groups also feed into her fictionalised K-pop world.

“Reading about the ‘black ocean’ that happened to Girls Generation,” she says, referencing the K-pop phenomenon in which fans intentionally withhold cheers, applause and phone lights as a silent, dark expression of displeasure with a group during a performance, “a lot of that was fodder for the kind of stuff that was happening in the book, too”.

But BTS, which were not launched by one of the big K-pop labels, made the biggest impression on her.

“If you look at the larger context of the culture where they came from, of being a very collectivistic culture where K-pop itself is a highly structured industry where everybody knows what the rules are and you sort of do what you’re expected to do, I really feel like BTS was super-idiosyncratic in the way they deviated from those expectations and moulds,” she says.

Ma-Kellams has several new projects, including a prequel focused on the professor and her husband in the years before Duri landed in their home. And she has an ongoing relationship with K-pop, thanks to all that research into songs, albums and music videos for the book.

“As a general music fan, I feel like K-pop has ruined my experience enjoying other musical acts,” Ma-Kellams says, laughing. “Because I’ll go to a concert, and I love live music no matter what, right?

“But I’m watching it and the cynical part of my brain is like, to an American or European or whatever band, I’m like, ‘Oh, you’re just prancing around on stage’.

“I’m like, ‘If this was a K-pop concert, they would be putting in way more effort. They would be doing choreography, they would be way more planned instead of just showing up and letting the music carry you through the concert. I appreciate the effort and the fact that the effort looks effortless.”