Twenty-five thousand screaming fans fill a darkened stadium, forming a sea of bodies and frantically waving glow sticks. Lights and fog dramatically set the stage. Cymbals clash; then suddenly, she rises up: the girl they’ve all been waiting for, belting out one of her chart-topping Japanese dance hits. Her name is Hatsune Miku. And she’s a hologram. Unlike the hologram that brought rapper Tupac Shakur back from the grave for a sensational Coachella performance on Sunday, however, Miku isn’t based on a real person. She’s entirely fictitious, an avatar created by the Japanese technology firm Crypton Future Media, using Yamaha Corporation’s Vocaloid 2—the so-called singer-in-a-box program that allows users to input lyrics and melodies, control elements like vibrato, and instantly pop out flawless vocals. Since she originated in 2007, Miku’s performed live for paying audiences of up to 25,000 people and was the face of Google Chrome’s promotion blitz in Japan (a post occupied in the U.S. by her popularity equivalents, Justin Bieber and Lady Gaga). She has her own video-game series and boasts a fan base so formidable that they threatened a Clash magazine writer’s life after he dared to use the word “slutty” when describing her somewhat risqué attire. Miku is, by all accounts, a teen pop idol.