On October 8, a very different musical guest took over The Late Show with David Letterman. Hatsune Miku, Japan’s favorite virtual idol, performed an English version of the song “Sharing the World” via the hologram technology previously used for her touring appearances.

Hatsune Miku is a singing synthesizer program, developed by Crypton Future Media and running on Yamaha’s Vocaloid 2 technology. Her voice is sampled from Saki Fujita, a Japanese voice actress known for roles in Attack on Titan and Durarara!!, among others. Since her initial release in 2007, she’s experienced massive popularity – hundreds of artists have used the software to make songs with her voice, plus multiple video games have been made based on her and other Vocaloid characters.

Miku’s appearance on The Late Show is not her first “live” appearance in the United States. She has previously performed at the Nokia Theater during Anime Expo 2011, and she also made an appearance as Lady Gaga’s opening act for a period of time during the “ArtRave: The Artpop Ball.”

While the crowd at the Ed Sullivan Theater seemed into it, Letterman himself seemed somewhat perplexed, saying, “It’s like being on Willie Nelson’s bus.”