Six years ago, South Korean actress Sophie Kim was a star in her country's musical theatre scene.

She had played the lead role in several Broadway musicals, including West Side Story, Fame and Rent, and had been in countless other productions.

There was no reason for her to rock the boat.

In 2010, however, after establishing a decade-long career in South Korea, she decided to leave her comfort zone and move to New York to see if she could further her career there.

It did not bother her that she spoke little English then.

"I was impulsive, but bold," she says of that decision.

The move paid off. This year, the 36-year-old became the first Asian to land the role of shy nun Mary Robert in the musical Sister Act, which opens here tomorrow at the MasterCard Theatres at Marina Bay Sands.

She is also the only Asian in this production, which is based on a 1992 film of the same name, starring Whoopi Goldberg. This is the first time the musical is playing in Singapore.

"This is a really big break," says Kim. "This show is very important to me because this role has never been given to an Asian before. It's a huge opportunity."

Born Kim So Hyang to a housewife mother and a taxi-driver father who also works in a book publishing company, Kim grew up with two siblings in the theatre district of Daehangno in Seoul. Her mother often took her to the theatre.

"I was exposed to the arts from a very young age," she says.

"There are no artists in my family, but I love singing and my parents harboured dreams of me becoming a star one day."

They were supportive of her enrolling in Anyang Arts High School at the age of 16, where she majored in acting and modern dance. It was during this time that she decided to develop into a musical actress.

After graduating as a musical theatre major from Kookmin University in Seoul, she made her stage debut in the musical Godspell in 2001.

Over the next decade, she chalked up an impressive resume as a musical actress in South Korea.

She stunned colleagues and loved ones when she decided to further her career abroad.

"They all told me, 'You have a career in Korea, why would you want to go to the United States to start all over again?'" she recalls.

But she was adamant.

Once overseas, she gave herself the name Sophie - "because people had trouble pronouncing So Hyang and because I like the English word, sophistication" - and plunged into studying musical theatre for a year at the New York Film Academy.

That year - as well as those that followed - was difficult, Kim says.

"I cried a lot. I woke up at six every morning to practise English. I had no friends. Everything was very tough."

Because of her challenges with the language, she was "rejected lots of times" at auditions.

She did find some work on Broadway in the US, with roles in musicals such as Miss Saigon and The King And I.

When she was not flying back to South Korea to perform in shows there, she also found work in New York as a voice coach.

Then, in February this year, she auditioned for Sister Act, got several callbacks and eventually landed the part of Sister Mary Robert.

"When my agent told me the good news, I could not believe it. It's unusual to cast an Asian for this role. I screamed in excitement, then I cried tears of joy," she says.

She adds that she loves the character's good-natured personality and especially enjoys her solo number, The Life I Never Led, where she sings about how obedient she has been, conscientiously following the rules.

Says Kim: "The song reflects my journey in America so far. I'm like her, trying so hard, trying to be polite to everyone I meet. I don't yell, I don't argue, even when there are all these frustrations I feel."

After this international tour of Sister Act, she intends to continue building her career in the US. Being in Sister Act has shown her that Asians can snag roles that are typically given to non-Asians.

"I want to continue to try to break barriers, to do things that are seen as impossible," she says.