It's not a hologram. In Japan, they actually had a thick, double-sided screen made of glass that projected the image of the Vocaloids inbetween the screens, making it seem like a very much, realistic and 3D hologram. The ones in America were just pretty much from a huge black screen. If you look at the videos carefully, I'm sure it's visible. Well, for the American ones, anyhow.
On topic:
MEXICO HAD A VOCA-CONCERT. AND WE DIDNT. What is this fallacey.
But if we ever do, I'd like to hear some new songs instead of those old songs. I'm sure people would be delighted to hear some Nem creations, Kagerou days, Envy Cat Walk, Datte Datte Datte,Senbonzakura, etc.

