The only thing connecting each tiny room at the Happiness Factory to the outside world is a feeding hole in the door.
No phones or laptops are allowed inside these cells, which are no bigger than a store cupboard, and their inhabitants have only bare walls for company.
Residents may wear blue prison uniforms but they are not inmates – they have come to the centre in South Korea for a “confinement experience”.
Most people here have a child who has fully withdrawn from society, and have come to learn for themselves how it feels to be cut off from the world.
Solitary-confinement cell
Reclusive young people like these residents’ children are referred to as hikikomori, a term coined in Japan in the 1990s to describe severe social withdrawal among adolescents and young adults.
Last year, a South Korean Ministry of Health and Welfare survey of 15,000 19- to 34-year-olds found more than 5% of respondents were isolating themselves.
If this is representative of the wider population of South Korea, it would mean about 540,000 people were in the same situation.
Since April, parents have been participating in a 13-week parental education programme funded and run by non-governmental organisations (NGOs) the Korea Youth Foundation and the Blue Whale Recovery Centre.
The aim of the scheme is to teach people how to communicate better with their children.
The programme includes three days in a facility in Hongcheon-gun, Gangwon Province, where participants spend time in a room that replicates a solitary-confinement cell.
The hope is isolation will offer parents a deeper understanding of their children.
‘Emotional prison’
Jin Young-hae’s son has been isolating himself in his bedroom for three years now.
But since spending time in confinement herself, Ms Jin (not her real name) understands her 24-year-old’s “emotional prison” a little better.
“I’ve been wondering what I did wrong… it’s painful to think about,” the 50-year-old says.
“But as I started reflecting, I gained some clarity.”
Reluctance to talk
Her son has always been talented, Ms Jin says, and she and his father had high expectations of him.
But he was often ill, struggled to maintain friendships and eventually developed an eating disorder, making going to school difficult.
When her son began attending university, he seemed to be doing well for a term – but one day, he totally withdrew.
Seeing him locked in his room, neglecting personal hygiene and meals, broke her heart.
But although anxiety, difficulties in relationships with family and friends, and disappointment at not having been accepted into a top university may have affected her son, he is reluctant to talk to her about what is truly wrong.