To look at 29-year-old Kenji Tanaka laughing and drinking with his friends, it's hard to believe that he spent the best part of his twenties cut off from almost all human contact.
He's at a weekly pot-luck party organized by New Start, a nonprofit organization based in the outskirts of Tokyo that is helping Kenji and other recovering "hikikomori" (socially withdrawn young people).
Estimates of the number of socially withdrawn young people in Japan range from the tens of thousands to more than a million. Many have been hidden for years. New Start's aim is to coax these young people out of their rooms and help them function again in Japanese society.