Last week on David Letterman, an anime character sang while a live band played. The audience watched in stunned silence. Check it out:

Meet Hatsune Miku, a make believe celebrity who (that) is hugely popular Japan. It sounds utterly crazy. Only in Japan right? But when you delve into its origin story, unbelievably, it makes sense.

Hatsune Miku started off as a mascot of sorts for a software company’s music-making program. Part of the software’s functionality is to provide a synthetic voice to sing the music users wrote, and the company brilliantly thought that creating a character — a face — behind that voice would differentiate their app.

Not only can you use her voice and likeness, you can even use the software to animate her so she can dance to the music.

Amateur songwriters responded by posting videos of her singing their songs. And people loved it. Hatsune Miku is like the first open source celebrity; a star with with a fan base anyone can use to represent their song. Yes, even you, who’ve never been in the music industry.

Before you knew it, Hatsune Miku had a massive following — beyond the music people wrote for her, to her actual likeness. She became a pop star not unlike Justin Bieber, except she’s not actually real of course.

It made me wonder whether something like her could work anywhere else outside Japan. I asked people what they thought — many responded that it’s strange because she’s not real, that she cannot be touched. But how many of us expect to come into actual physical contact with a real celebrity anyway?

Whatever the case, she has clearly connected with an audience in Japan. As you can see from this concert:

If you’re interested in learning more, I recommend this fantastic video from Polygon: