She is considered to be Black★Rock Shooter's prototype and is voiced by Miyuki Sawashiro. According to Gray's game trailer she has a very close relationship with BRS and sees herself as a 'not failed but not successful' creation.
Gray's weapon of choice is a longsword with two tooth-like peaks at the edge and a black and orange color scheme.
Nana is one of the 22 2nd-generation combat clones born to combat the alien invasion. Unlike her 21 other sisters, she was born a day later on 7th July 2034 due to problems in equipment.
- She seems to be the one who helped the human forces vanquish the eight aliens on the earth in the past.
- In the True Ending. It was shown that Nana Gray was alive and wasn't "nebladed" by an alien or White Rock Shooter her self and was with Black Rock Shooter in the Lab when the credits starts rolling.
- There was a running gag of Nana Gray from one of her missions where she went "yandere" and became all girl-like attitude saying "Where are you~? Where Are you~?! I'm right here~!" after you finish the mission BRS will act "yandere" as well and be all serious like Nana Gray.
- Despite wielding a sword on her artwork, Nana is never seen using it in the game. Instead, she wields the weapon 7-shots, a weapon used by BRSB.
- The name "Nana" is "seven (7)" in Japanese. While Nana originally thinks that her name was just a number, the reason behind her name is revealed from Professer Gibson's message in her teddy bear in the better ending. Nana is named so as she was born on 7th July at 07:00, and as Professor was born on the 7th as well and that he likes the Japanese word for "7" the most among all other languages he chose the name "Nana", and at the end of the message he implies that also viewed Nana as a very special child to him.
- Gray possesses a test version of Stella's Bike that is depicted with an orange and black color similar to her own color scheme.