On her own, Japanese pop superstar Hatsune Miku can't sing. Nor can she rap, dance or DJ. She is drug- and alcohol-free because she can't indulge in either, and she can't have affairs or engage in offstage shenanigans fit for YouTube scandals or tabloid headlines. Now entering her sixth year as a beloved idol with a global fan base, she looks as youthful and demure as she did when she debuted. She can't even get old.

"She doesn't exist," says her creator, Hiroyuki Itoh, with a brief shrug. "Never has."

Itoh, CEO of Sapporo-based Crypton Future Media, is a software developer and so-called meta-creator, whose goal is to aid others in realizing their artistic endeavors. In 2007, he asked a graphic artist named Kei to create an anime-inspired digital avatar, the kind of cartoon-company mascot common in Japan, to represent both Crypton and its virtual-voice program for Yamaha's Vocaloid software — a singing-voice synthesizer.