Hatsune Miku
Since the success of her Vocaloid 2 package led to an expansion of marketing possibilities, most of the mass marketing has come after her initial release as a response to her popularity and has been on going since 2008. Even with the addition of other Character Vocals, Miku's name continues to be used as the primary source of marketing for Crypton Future Media, to the point where most products for their Vocaloid related products will usually only feature Hatsune Miku's name. In March 2012, the Nomura Research Institute estimated that the sales of all Hatsune Miku brand goods added up into the region of since her release in 2007. Her name is easily the most recognizable of all Vocaloids.
Supercell (band)
Ryo chose to distribute his music on Nico Nico Douga because he liked the website along with its response system, which enables user's comments to appear overlaid on the video screen. Ryo did not originally intend to use Hatsune Miku as the vocalist for his songs, and most members of Supercell did not even know of Miku until after "Melt" gained popularity. Since Ryo did not know any singers, he was recommended by his friends to use Miku, which he thought was a good idea since videos using Miku were already widely being distributed on Nico Nico Douga at the time.