The unassuming, slight, 62-year-old may look every bit the timid retiree but to the thousands of Nepalese girls she has rescued from a life of sex slavery she is the heroine they call "saviour".
Anuradha Koirala left teaching 18 years ago to devote her life to waging war on the traffickers who smuggle women and children into the brothels of India, where they are often raped, assaulted and starved.
From setting up a safe house in Kathmandu to a daring undercover raid on a Mumbai brothel, Koirala says she has helped more than 10,000 victims of a cruel underworld which sees victims trafficked daily across the border.
"I wish for a day when I don't have to look after any more victims," she told AFP. "I want the sex trafficking to end."
An estimated 12,000 Nepalese girls are trafficked each year, the victims of a cycle of unemployment, poverty, gender discrimination and a 10-year Maoist insurgency which wrecked the economy and ruined countless lives.
Some estimates put the number of victims trapped in India's lucrative sex industry at 200,000, while local NGOs in Mumbai have reported that about 40 percent of girls rescued from Mumbai brothels were Nepalese.
Koirala decided the misery had to end and in 1993 set up a charity she named Maiti Nepal -- using the Nepali word for "mother's home".
In August 1999 she risked her life to travel to Mumbai's most notorious streets, where mostly underage Nepalese girls are forced by brothel owners to sell their bodies to locals, businessmen and sex tourists.
In Kamathipura, the city's red light district, she pretended to be a fan among the entourage of the late actor and lawmaker Sunil Dutt, who was well-known for his social work visiting brothels and talking to sex workers.
But her cover was blown and the visit turned violent.
"The rescue was quite bizarre. The majority of the brothel owners turned out to be Nepalese who had themselves once been victims," said Koirala.
"It turned violent. The brothel owners and their aides started to hurl shoes and kitchenware at us. They even tried to hide the girls.
"They were mostly underage girls, many of them barely 12, and were kept in a structure where it was difficult even to breathe," she added.
Koirala, a mother of one, set up Maiti Nepal in Kathmandu after meeting dozens of homeless victims of domestic violence whose children were identified as a prime target for sex trafficking rackets.
She launched a network employing the women to sell cigarettes, chocolate and snacks from woven bamboo trays, and then rented a house to shelter 80 of the women's children.
Koirala's work now extends to the countryside around Kathmandu, where a centuries-old trade in sex trafficking is burgeoning.
Young and middle-aged men trick poor, jobless village girls into marrying them with promises of work in the cities, only to sell their new brides to Indian brothels.
The victims have their drinks spiked while travelling and are diverted to brothels, Koirala said.
"They usually find themselves in a strange place where an unfamiliar language is spoken," she said. "And from then, their life of misery begins."
One 16-year-old whose identity AFP is protecting had moved with her family to northern India and was trafficked into sex slavery by a 22-year-old man promising her a job in Mumbai.
"If I did not have sex with men, they would not give me food and torture me for hours," she said.
For 10 months her life was a living hell until she was rescued in a brothel raid by Maiti Nepal and local police two years ago.
Now studying in a school run by Maiti Nepal, the girl, who doesn't know where her parents now live, described Koirala as her "saviour".
"I had never imagined I would come out of the hell. I got new life which wouldn't have been possible without her," she said.
"I feel blessed to be able to get her love. Now, she's like my mother."
Maiti Nepal, whose growing list of patrons includes actresses Joanna Lumley and Demi Moore, came to the attention of the global media after Prince Charles visited in 1998 and donated more than $100,000 from the sale of his paintings.
It now boasts a sprawling complex of offices, a shelter, hospice and school, as well as a network of anti-trafficking checkpoints along the country's porous border with India.
Koirala, a recipient of the CNN Hero award last year, believes the fight against sex slavery is more important than ever.
"Now, the girls are trafficked to Middle East," she told AFP. "And domestic trafficking has significantly increased. Young girls from rural areas are lured into Kathmandu's thriving sex industry."
Koirala says shutting down her charity is her ultimate goal.
"I want to do this not because I'm tired of the work but because I don't want this problem to continue forever."