For nearly two years, a group of Japanese cleaners has been quietly tidying up Singapore's parks and streets.
But they are not new recruits to the 70,000 or so cleaners here. They are expats who do so for free, out of love for their temporary, adopted home.
Once a month, up to 15 of these cleaners - who are members of Tokyo-based non-profit environmental group Green Bird - head out in a uniform of matching green vests to tourist spots such as East Coast Park and Little India to spend an afternoon picking up trash.
Being responsible for keeping one's environment clean is a value that is taught to Japanese from a young age, said volunteer coordinator Junko Kurata, who moved here in 2011. She declined to give her age.
"You have to take care of your country to keep it clean. You don't just throw all the responsibility to someone else," she told The Straits Times, referring to Singapore's heavy dependence on cleaners.
While out picking up litter, the group - which comprises mostly female professionals above 30 - takes time to explain their philosophy to curious Singaporeans who approach. But most passers-by are oblivious, she said, with many not even noticing their work.
It is something she is determined to change. Even though Green Bird's Singapore chapter has so far attracted only Japanese members, the group is open to all.
Her hope is to eventually hand the group over to Singaporeans dedicated to its message that cleanliness begins with personal responsibility.
Green Bird originated in 2003 in Tokyo's Omotesando neighbourhood, after politician and resident Ken Hasebe grew perturbed that he could still find litter, such as cigarette butts, in the streets.
The Japanese group, which receives financial backing from sports goods giant Nike and Tower Records, now has thousands of volunteers across Japan, and chapters in Paris, Sri Lanka and Ghana, too. The funding provides gear like vests, gloves and garbage bags.
Why Singapore? Green Bird sprouts spontaneously wherever its members move to, Ms Kurata explained.
"We feel strongly about this. We just don't feel comfortable when we see litter. It makes us want to pick it up. It doesn't matter that a place is not our home town."
Added volunteer Norie Abe: "It is natural for Japanese. In Japan, students clean their classrooms every day."
Litter-picking sessions to change mindsets have grown more common here as pioneers like Keep Singapore Clean Movement head Liak Teng Lit and MP Lee Bee Wah seek to turn Singapore from a "cleaned" city into a "clean" one.
Ms Lee has organised monthly litter-picking sessions - unrelated to Green Bird - for residents in her Nee Soon South ward since last October.
More than 20 other neighbourhoods and wards have since followed suit.
Singapore Kindness Movement general secretary William Wan said Singaporeans could learn from foreigners' love for a city not even their own.
"This may not be their permanent home, yet they love our city and want to keep it clean," he said.
"This is our home. Shouldn't we take more pride in it and keep it clean by not littering?"
Green Bird Singapore will next meet at East Coast Park on Sept 29. Contact the group at firstname.lastname@example.org