One morning, just after she turned 14, Kanako Mizoguchi woke up and decided she had had enough of school. "I still find it hard to describe why," she says. "I felt like I was becoming invisible, like I was being rubbed out. I really thought I was going to explode and do something bad."
Kanako spent five years in her room, sleeping 12 hours a day, reading books and connected to the world only through her computer. Now 20, with a sharp and witty personality hiding behind a sullen distrust of authority, she is recovering from a phenomenon that afflicts the lives of thousands of Japanese families: hikikomori or social withdrawal.
"Monsters in the house", is what one author calls Japan's confused and angry children, who are dropping out of school in record numbers: 120,000 officially but probably many more. If not treated, many children become full-blown recluses and never return to society. And as the country has discovered after a series of ugly murders in the past month, some can become very dangerous indeed.
Masaru Iijima had locked himself away in his room for eight years when he bludgeoned and stabbed his parents and older sister to death last month, days after another 19-year-old recluse used a 4kg iron dumbbell to kill his parents in the same prefecture.
Both families were, on the surface, pictures of middle-class stability; Iijima's father worked as a deputy curator at a local museum, and the 19-year-old's parents were both teachers. But behind the walls of their suburban homes, there was enormous tension, periodically broken by explosive bursts of rage by the young men, both of whom had attacked their family before.
Iijima's married sister regularly visited to try to persuade him to get a job and avoid conflict with his father who, the son's police statement said, was killed because he had "robbed me of my space to live in".
The men, like 36-year-old Kenichi Ito, who had shut himself in his room since he was 16 before strangling his elderly mother and father in October, fit the standard recluse profile: quiet, serious types who mostly lived at home with uncomprehending parents afraid, or unwilling, to throw them out.
Parents and offspring often avoid contact by entering and leaving the house separately, and use bathrooms and kitchens at different times. In one case, a man kept a young girl captive in his room for nine years. "I knew there was something going on but I was afraid to go into his room," said his mother.
Dr Tamaki Saito, a psychiatrist who has written a best-selling book about the social recluses, says: "My worst case is a 45-year-old man who has been holed up for 30 years. His parents hardly ever see him because he gets up at midnight to eat and read and goes back to sleep before his parents are up."
Dr Saito, who believes there could be as many as one million people suffering from social withdrawal in Japan, runs the only clinic in the country that treats the disorder. "This is a growing problem and needs to be tackled otherwise we are going to have more cases of violence in the home."
Most recluses are a danger only to themselves, as a recent spate of group suicides confirms. Many are using the internet to seek out fellow sufferers, a small number via websites that arrange suicide pacts.
Kanako says: "I thought about suicide a lot but I didn't have the courage." Her favourite book while she was a recluse was One Hundred Years of Solitude, by Gabriel García Marquez.
Most hikikomori problems develop in the mid-teens, when the pressure from Japan's exam-driven education system, begins to ratchet up. Kanako was lucky, rescued by a unique Tokyo treatment centre that uses a mixture of psychotherapy and progressive teaching methods. Run by Satsusugu Kudo, the Youth Independence Support Centre has been operating for almost 30 years, purely on funding from parents and benefactors.
"We can cure it if the kids come to us young, but once they reach their 30s or 40s, it's really difficult," Mr Kudo says. "It's worsened as Japan got richer and the old sense of community has broken down, pushing people into their boxes. It is hard to see how it will end."
Kanako says she at least is confident she will get better: "I can talk things out here with others, so I no longer feel I'm invisible."
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