The Japanese apparently have a fetish for clinical cleanliness. They can't seem to stand dust, let alone pigs wallowing in garbage - a common sight in Calcutta, which is rapidly degenerating into a byword for urban squalor, poverty and disease in developing countries.
Yet today - the seventh anniversary of Mother Teresa's death - young men and women from Japan outnumber volunteers from countries around the world working at various centres for the city's destitute and dying run by nuns belonging to Missionaries of Charity (MOC), the order she founded in 1952.
There are as many as 200 overseas helpers in 19 Calcutta facilities, ranging from orphanages to homes for the dying and shelters for lepers and the mentally ill, run by the MOC.
The helpers are mainly from Japan, Korea, the United States, Britain, Germany, Australia, Italy, Spain and South Africa.
Sophia Heyland, barely 19, arrived from Munich last month as a tourist. Within days, she had signed up as a volunteer at Shishu Bhavan, the orphanage for handicapped children.
'I was shocked by the poverty and misery all around, particularly small children begging and falling at my feet for a slice of bread. So I decided to cut short my holiday and work for them,' said Ms Heyland, who plans to return for a longer stint next year.
An American who refused to give his name said 'the whole order has an aura', summing up the sentiments of the helping hands from abroad.
'It is blessed to be here. It is us who are lucky to be here, rather than the sisters. We get more by being here than the people we serve or the sisters get from us.'
They spend their own money on air tickets, hotel and local travel to work among the poorest of the poor. Some of them are doctors, paramedics or trained social workers giving up their holidays.
Much of the work, after all, does not require technical skills. At Nirmal Hriday and Prem Dan, homes for the dying and the mentally ill respectively, foreigners wipe floors, clean bedpans and shave, bathe, massage and feed Indian society's rejects.
At Shishu Bhavan, near Mother House - the global headquarters of MOC - European girls feed babies, change nappies, play with them and clean up when they throw up.
They can also be seen holding hands, singing and laughing with lepers rehabilitated at the Titagarh facility after treatment.
The trademark white saris with blue border worn by MOC sisters the world over are woven at Titagarh by lepers who have recovered.
Mother Teresa once described helpers as 'beautiful people with a beautiful spirit who make many sacrifices to provide tender love and care'.
No doubt, Mother Teresa was the magnet who pulled them to Calcutta. So when she died on this day in 1997, many thought the order would lose support.
But such dire predictions have been proven wrong, says Sunita Kumar, businesswoman-cum-socialite-turned spokeswoman for the internationally known nun's order.
'The number of volunteers has trebled,' Ms Kumar said.
'When Mother Teresa was alive, around 50 new helpers enrolled every month. And now 150 are turning up. It's a tribute to Mother's legacy and the good work the sisters are still putting in.'
She also said donations - the order's lifeline - had not dried up. Many big donors, including individuals as well as corporate representatives, call Sister Nirmala, Mother Teresa's successor, regularly to assure her they will be always with MOC.
Moreover, Ms Kumar stressed that the number of homes run by MOC worldwide had increased to 710 from the 600 on the books seven years ago.
She said there had been very few helpers initially. But after Mother Teresa's Nobel Prize in 1979, young men and women, as well as widows and widowers, began flocking to Calcutta from all over the world.
'Mother would tell them to enlist at MOC centres in their countries instead of coming all the way to Calcutta and coping with the heat, dust, monsoons and mosquitoes,' she said.
'But she was such a big attraction that everyone made a beeline for Calcutta, virtually turning it into a place of pilgrimage.'
Some young people who met and fell in love while helping in Calcutta got married and were specially blessed by the sisters in the historic chapel at Mother House.
Ms Kumar revealed that some helpers came from the royal families of Spain, Belgium and Sweden, but did not elaborate.
Apart from India's heat and dust, helpers have to contend with policemen.
Indian visa rules specifically prohibit voluntary service. So authorities sometimes refuse to grant an extension if they know the applicant is working as a volunteer.
Despite the difficulties, many helpers return for the second, third and even fourth time. Some have been to Calcutta nine times.