“A little old, two sisters just had spent life on the streets of the idyllic countryside.
They flee, while supporting each other, passed the parent happily. One day, the younger sister did run up to the older sister, the stomach of the younger sister was penetrated with the enormous sword of the older sister.
The younger sister don’t recognized the reason, deteriorates and falls.
Black wings and horns grew from the older sister in front of wierd skulls, the older sister disappeared infront of the younger sister.
The sister survived by a miracle regaining consciousness,
the town wakes up to her and her people had been thoroughly destroyed by the massacre.
The older sister and her, were the persons who said once Dead Master needs to be destroyed,
the Bone Legion soldiers will be notified, the emergence and transformation of her at the same time.
Dead Master leading the invincible bone soldier corps, in order to ruin all mankind, had started conduct. The bone soldier intelligence is low, their attacks are just like those from dogs but struggle not only against simple attacks. They reject any attack on their side.
They also avoided the specter of weapons and bullets to exist as a substantive.
The army can be defeat, the only bone that is decorated with weapons attacks by a special processing…
The people just had few weapons, but didn’t handle.
BRS is an ancient weapon that can be made against bone soldiers which would help the younger sister. Rock Shooter and Black Sword were received and the older sister stops, the variable motorcycle, becomes the moonlight circle and also appears traveling as a Black Rock Shooter..
Then a few months later, she awakened from a nightmare and is lying in ruins standing in the middle of the journey. ”
However, the story is way to long…
Mainly BRS is the codename of the members of a organisation that fights against the evil spirits that have taken controll over some people like the older sister of “BRS” which turned to Dead Master because of them. The only way to rescue her sister was killing her. After a fusion of all those skull soldiers appeared which was the last enemy to kill to get peace at the world again…

They have identical clothes, but the face and haircut differ a lot; there are no similarities with Miku.
Huke might have published his first Miku look-alike BRS afterwards, when ryo/supercell asked him to affliate with him for the song, and huke simply re-designed his BRS to look more like Miku.

If that was the case, the BRS from then IS a Miku look-a-like, since that wasn't how she looked prior to that.
The oldest BRS Miku I've found on his blog was in end 2007, way after Vocaloid 2's release and around the time the song itself came out.

"it was one of his very first designs even thought she don’t had her final outfit at that point", about that, I didn't find out which pic you were talking about. I've checked his doujin 'HUKEPIC' 01-05 works and his other stuff, but no luck there.

This just seems like BRS looked the way she look before (different face & haircut), and was simply redesigned as a Miku look-alike (familiar expression, long twintails). I'm not one of those who considered that long twintails = Miku clone, because Miku was far from the first in looking like that, but if it's something released afterwards and even has the same face, I think calling them such would be justified.

If you can show that BRS picture that looked like Miku before Miku's first design was even done, then by all means do so, but I had no success in finding it myself.