ハジメテノオト (Hajimete no Oto)

Background
This song was uploaded to Nico Nico Douga on October 13th, 2007. It currently has over 2,000,000 views on Nico Nico Douga and is one of Miku's early hits.

It is also featured in the Miku no Hi Kanshasai 39's Giving Day concert, the MikuNoPolis concert, the Miku no Hi Dai-Kanshasai 39's Giving Day 2012 concert and in the games Project DIVA 2nd and Project DIVA Arcade.