As Black Rock Shooter continues to struggle against Chariot and Dead Master, Mato waits at the festival for Yomi, but she never arrives as Kagari wouldn't let her. As Mato dreams that night of Black Rock Shooter, who had a heart scarred on her chest, she discovers Yomi has the same scar the next day, yelling at her for having no spine. After consulting with Saya, who tells her dreams serve a deep meaning between friends, Mato goes to Yomi's house, but Kagari stops Yomi from coming to see her by throwing herself down the stairs. As Kagari is taking into hospital for a twisted wrist, Mato hears from Yomi's mother about how Kagari was hit by a car whilst chasing after Yomi, demanding she look after her. Determined in her belief that Yomi shouldn't suffer for that, Mato voices her pleas to go home with Yomi, calling her by her first name. Mato helps Yomi realise her true feelings, wanting to be earnest friends with both Mato and Kagari. As Dead Master manages to break free from her binds, but she is captured by another evil, Black Gold Saw, whilst Black Rock Shooter is forced to kill Chariot, which has its effect on Kagari.
On the first day of junior high school, Mato Kuroi happens to run into Yomi Takanashi, a shy, withdrawn girl whom she immediately takes an interest in. Mato tries her best to make conversation with Yomi, wanting to befriend her. At first, she is avoided, but the ice breaks when Yomi happens to notice a decorative blue bird attached to Mato's phone, which is from the book "Li'l Birds At Play." Discovering they have a common interest, the two form a strong friendship.
In an alternate universe, the young girls exist as parallel beings, Mato as Black★Rock Shooter, and Yomi as Dead Master. Somehow, what happens in one world seems to have an effect on the other, and unaware of this fact, the girls unknowingly become entangled by the threads of fate.
