At other than Japan, the favorite of Miku is recognized to be a "leek" (韮, ニラ, nira, Garlic chives, Chinese chives). However, in Japan, the favorite of Miku is a spring onion (葱, ネギ, negi, Scallion). This misunderstanding continues till now from the times of "Loituma Girl" which is the cause of the setting of the "negi" enthusiast of Miku. In Japan, it is recognized that the leek is a different plant from the spring onion although they resemble each other.
Origin of "negi"
(Origin 1)(the part of 5:19~)
"Bleach" ep2
(Origin 2)(Song)
Loituma - Ievan Polkka
(Origin 3)(So called "Loituma Girl","Leek spin")
Loituma Girl
And then, the greatest Vocaloid video (made by Otomania in Sep.04.2007)(picture by Tamago)
"Ievan Polkka"