Singaporean writer Lee Jing-Jing dreams of her characters.

"It's like watching a movie sometimes," says the 32-year-old. "They become real for me - it goes on for months and months. I let myself be taken over by them."

Five years ago, she began dreaming of an old woman who had been forced by the Japanese to be a comfort woman during World War II.

The woman, who had appeared in a previous novel of Lee's, would not leave her alone. "I realised I wanted this voice to be heard."

The woman in her dreams planted the seed for her international debut novel How We Disappear, which looks back at the Japanese Occupation of Singapore during World War II and is expected to come out in the second half of next year.

It was picked up last month for a five-figure sum by Oneworld, the British publishing firm behind the last two winners of the prestigious Man Booker prize - Marlon James' A Brief History Of Seven Killings and Paul Beatty's The Sellout.

Set at the turn of the millennium in Singapore, the novel follows a 12-year-old boy whose dying grandmother mistakes him for his father and lets slip a secret about his origins.

Going in search of his real family, his path crosses that of elderly widow Wang Di, a woman whose history is marred by what she endured in the war.

Lee, who lives in Amsterdam and is married to a Dutch political scientist, has pursued a writing career for the past 10 years.

Having her book picked up was "as much a relief as it was exciting", she says over the telephone from Los Angeles, where she is on a break.

"I had been working on this novel for five years and I was confronted with the possibility that it might never see the light of day."

She is the author of two books in Singapore - the poetry collection And Other Rivers (2015), published by Math Paper Press, and the novel If I Could Tell You (2013) with Marshall Cavendish, which follows the residents of a doomed Housing Board block as they struggle to cope with its impending demolition.

To flesh out her character for How We Disappear, she read numerous accounts by ex-comfort women and watched documentaries about their wartime ordeals of sexual slavery and forced sterilisation.

It was harrowing, she says. "These are women who could be your relatives, your aunts. Humans do horrible things. It does not make one optimistic about the world."

Oneworld co-founder Juliet Mabey says Lee shows "a real maturity unusual in a debut".

"It takes you into Singapore in World War II, but unusually - for people living in our part of the world, that is - not from the perspective of British soldiers or the expatriate community, but from the point of view of Singaporeans, which is not something we come across often.

"She has a tremendous flair for characterisation. If you're asking readers to go somewhere unusual and complex in a dark period of history, they have to relate to the characters taking them there."

Lee prefers to write about women. "When women write about women, they get criticised for being domestic, soft, feminine, but I just want to do it anyway. There are so many fantastic stories about women that people don't know."

Among her writing inspirations is the Tamil poet Salma, who was locked up at home when she got her period at the age of 13 and pressured to marry.

She would steal pieces of the newspaper used to wrap the vegetables her mother bought from the market, and wrote her poems in secret in the bathroom. She has since become an established writer and a politician. "It is such an incredible story," says Lee.

She joins a growing array of young women authors from Singapore with work going out into the world in a wide spectrum of genres.

She cites Rachel Heng, whose dystopian novel Suicide Club will be out around the same time as hers; Singapore Literature Prize- winning author Amanda Lee Koe; and Cheryl Tan Lu-Lien, author of pulpy bestseller Sarong Party Girls.

"There's not just one note. There are all these different voices. I think it's wonderful that there are so many writers on such a small island."