ブラック★ロックシューター (Black★Rock Shooter)

Interpretation
Black★Rock Shooter tells of the narrator's despair and hopelessness as they wander aimlessly, searching for something important to them that they presumably lost. Eventually the narrator gains new hope and decides to move on into the future with courage. The video for the song became massively popular, featuring Black★Rock Shooter traveling through a bleak city and countryside, riding a motorbike and wielding weapons. With little explanation as to what she is, it spawned a Fanbase that is dedicated to find the answers.

About the Character And Hatsune Miku
Although her appearance is similar to Miku, BRS is NOT a variant or derivative of Miku and only became associated with Vocaloid due to the popularity of the song. Both are entirely two SEPARATE entities not the same "person".

Black★Rock Shooter is a character created by a Japanese illustrator Huke. She is a 15 year old girl who attaches a cannon on her left arm, and the cannon shoots 20 rock bullets per second. Her Pigtails are not proportional, one part of her Pigtail's is shorter than the other. She has scars around her stomach and hip, and has a blazing blue eye. Black★Rock Shooter is an original character design by Huke. Though she happens to resemble Miku, she is not a fanmade character/mascot derived from Hatsune Miku. Ryo asked Huke to use the character he designed as a motif of the song he would write.

This song has also appeared as sheet music in the Vocaloid Best selection series. This song also featured in the mook ボカロ☆バンドスコア.

Trivia

 * Another common mistake with the Western fandom is viewing the derivative known as Zatsune Miku as being influenced by Black Rock Shooter, this is debunked because BRS was introduced in December 2007, while Zatsune was introduced October 2007. And prior to that fan artwork of Zatsune's initial design can be viewed being before songs debut.