When I joined the couple for lunch at their favorite all-you-can-eat salad bar in the Tokyo suburb of Hachioji, he insisted on being called only by this new nickname, addressing his body-pillow girlfriend using the suffix "tan" to show how much he adored her. Nemutan is 10, maybe 12 years old and wears a little blue bikini and gold ribbons in her hair. Nisan knows she's not real, but that hasn't stopped him from loving her just the same. "Of course she's my girlfriend," he said, widening his eyes as if shocked by the question. "I have real feelings for her."

Emma (not her real name), 43, the only British member of the community, suffers from Asperger syndrome -- a condition which seems to be shared by around half of OS people. Asperger sufferers often have difficulties forming relationships with other people, and Emma's fixations are radios and hi fis. When I met her, she was in love with a hi-fi system which she called Jake. Jake, she says, is "solid, reliable and beautiful". She repairs "him" when he goes wrong, and "makes love" to him on average twice a day. "This is the way I communicate with him."