The 2011 tsunami in Japan that caused nuclear accidents and left nearly 230,000 people homeless had an enduring effect on software developer Abraham Yeo.
The 38-year-old was in north-eastern Japan in 2012 on a disaster relief mission and although almost eight years have passed, he vividly recalls the words of the survivors he had helped.
"They felt they were forgotten and left behind," he told The Straits Times. "They kept saying, 'Please don't forget us'. That really stuck with me."
With their words in mind, Mr Yeo began to realise that even in Singapore, there is a group of people who are in plain sight, but Singaporeans fail to notice their plight.
These people sleep rough in void decks, playgrounds and sometimes, in 24-hour cafes.
"When I returned to Singapore. I started to notice homeless people around. I realised they felt forgotten too," he said.
In 2014, Mr Yeo and a friend started Homeless Hearts of Singapore, an outreach group that befriends and gives food and drinks to rough sleepers.
Today, his charity has about 30 volunteers who meet about twice a month, before breaking up into smaller teams to visit different areas to befriend the homeless.
Beyond giving them the bare necessities like food, he said it is important to also build a relationship.
"We don't just want to give them food and walk away. We want to sit and talk to them as friends," he added.
"People do not become homeless because they run out of cash, they become homeless because they run out of relationships.
"There is more to homelessness than just helping them get a place to stay."
In July, his charity teamed up with Mount Alvernia Hospital to hold a free healthcare event for the homeless. The hospital now gives subsidised treatments to homeless patients referred to it by Homeless Hearts, at its clinics in Toa Payoh and Redhill.
The charity also joined a collaborative government effort called Partners Engaging and Empowering Rough Sleepers this year, in which officers from agencies like the Ministry of Social and Family Development accompany volunteers on their regular night walks to offer rough sleepers help such as money or housing.
Said Mr Yeo: "We want to journey with the homeless, whether it's just to talk to them or help them get a rental flat or financial aid.
"We celebrate with them when they get a home and we keep in touch with them, even after that. What we have is a friendship."
