ブラック★ロックシューター (Black★Rock Shooter), the anime, is based on the titular character, who was originally illustrated by huke. The first animated pilot was released September 30, 2009 on DVD. The second animated pilot aired online July 13, 2010.
The anime was release in Japan on July 24, 2010, and also broadcast online and subtitled in multiple languages.
Kuroi Mato entered junior high school and met Takanashi Yomi, who was her classmate. They were opposite in temperament, but they became friends through their student life. After they advanced to the next year, they were separated into different classes and get estranged. At the same time, in the different world, Black★Rock Shooter, a girl whose eye has a blue flame, and Dead Master, a girl who has a big jet-black sickle, have been engaged in deadly combat. 
For full Synopsis see Black★Rock Shooter (OVA) on the B★RS wiki.
Huke, a Japanese illustrator, designed a female character and posted an image of her on his Blog and Pixiv on December 26, 2007. This illustration of the character (given the name Black★Rock Shooter) inspired an upcoming producer named ryo, who was already a known songwriter on Nico Nico Douga and also lead member of supercell. Ryo requested huke to illustrate for the song he would write, as well as using the character within the video. Thus the character, Black★Rock Shooter, was the focus of the PV and song of the same name. It was posted on Nicovideo June 13, 2008. It was produced by ryo using the Vocaloid Miku Hatsune, and completed in collaboration with huke, who is now a member of supercell.
The song and video proved to be a hit among Vocaloid fans, and many fanmade artworks were created. One of the popular fanmade PVs is a 3D Promotion Video by Anomaro-P, which shows is a plotline and back-story of Black★Rock Shooter with Anomaro-P’s own interpretation.
The great hit song eventually became the inspiration for the 2010 OVA. The animation of OVA is strongly based on the original art style of huke, and many of the scenes in the pilot were based upon the original supercell video. Although the OVA was delayed by one month, there was merchandised that was bundled with the DVDs to make up for the delay. 150 readers got the chance to see the OVA before the sale, (note: applies to Japanese citizens only).
These are Primary Characters of the Black Rock Shooter Universe:
* Black★Rock Shooter (ブラック★ロックシューター) lives in a different world than that of Mato and her friends. She is a young girl with blue fire residing in her eyes. She fights with her ★rock Cannon, a weapon capable of shooting 20 rock bullets a second. Mato Kuroi (黒衣マト; Kuroi Mato) is an innocent and naïve junior high school student. She takes an interest in, and speaks to a girl she sees the first day of school, Takanashi Yomi.
In the OVA she is voiced by Kana Hanazawa
* Dead Master (デッドマスター) is a young girl who maintains a violent battle with Black Rock Shooter. She wields a jet-black weapon, Death Scythe. Yomi Takanashi (小鳥遊 ヨミ; Takanashi Yomi) meets Mato the first day of school. She is a somewhat mature young girl.
In the OVA she is voiced by Miyuki Sawashiro
* Yuu (ユウ) is a classmate that Mato becomes good friends with after starting her second year at the junior high school.
In the OVA she is voiced by Kana Asumi
These are Secondary Characters of the Black Rock Shooter Universe that appear in the OVA:
* Black★Gold Saw
Screenshot from the Black★Rock Shooter Anime pilot
Angel EmfrblAdded by Angel Emfrbl
The official pilot was released on Japan Amazon for preorder, it was made for sale on the 30th of September 2009.
A number of promotional figurines have already been released based on the character and the OVA is set to be released in July. Distributed in the following magazines:
* Monthly Hobby JAPAN (September issue) – 24 July 2010
* Megami Magazine (September issue) – 30 July 2010
* Animedia (September issue) – 10 August 2010
* Though the Black★Rock Shooter song can be heard in the promo videos, for legal reasons Miku Hatsune could not be used in the actual OVA, although the musics instrumental score can still be heard throughout the OVA.
* As viewers watched the original PV, they noticed that B★RS and Miku appeared similar by design. It should be noted that Black★Rock Shooter is not derived from Miku Hatsune, nor is she a Vocaloid.
* The overall facial features of Black★Rock Shooter and Dead Master were altered for the OVA to match their real world counter parts more. Notably, however the original promos showed the characters more closer to the original artwork.