Didn't even think of that, I guess it's possible. I figured that those 2 were Miku and Rin. Wasn't sure who the middle person was at the time. I guess if it's Hidamari Sketch that's up to the panel of Hidamari fans.
Could be Yuno Miyako and Yoshinoya but Miyako never has twintails and Yuno always has that X in her hair, though the twintails could be a Miku thing, either way Rin's not in here.
However I don't have a leek. If it's possible, I would like to have one.
They're singing Miku Miku Ni Shite Ageru: Hatsune Miku's theme song.