As many as a million young people in Japan are thought to remain holed up in their homes - sometimes for decades at a time. Why?
For Hide, the problems started when he gave up school.
"I started to blame myself and my parents also blamed me for not going to school. The pressure started to build up," he says.
"Then, gradually, I became afraid to go out and fearful of meeting people. And then I couldn't get out of my house."
Gradually, Hide relinquished all communication with friends and eventually, his parents. To avoid seeing them he slept through the day and sat up all night, watching TV.
"I had all kinds of negative emotions inside me," he says. "The desire to go outside, anger towards society and my parents, sadness about having this condition, fear about what would happen in the future, and jealousy towards the people who were leading normal lives."
Hide had become "withdrawn" or hikikomori.