The disconnect between the Supercell trailer and what you actually watch is violent. You come in expecting a girl-with-a-gun action story and get a quiet, aching portrait of two friends drifting apart in real time. The animation and art direction are so clean, so deliberate, that watching Mato and Yomi's friendship fracture in slow motion becomes unbearable. The other world exists only in glimpses, a visual echo of emotional distance that never explains itself. The pacing moves like real adolescence: small moments, long silences, the horrible realization that people can drift without either of them meaning to. If you go in knowing you're watching a friendship break, the OVA becomes something closer to beautiful.

Mato Kuroi meets her classmate Yomi Takanashi on her first day of junior high school. Mato is innocent and straightforward while Yomi is more mature, and though Yomi is taken aback at first, the two soon become close friends who spend every day together. Mato gives Yomi a blue star phone charm that matches her own. When their second year puts them in separate classes, they begin to grow apart, and Mato spends more time with Yuu Koutari, a girl from the basketball team. Before long Mato cannot find Yomi anywhere. Meanwhile, in another world, a girl with blue fire in her eyes called Black Rock Shooter faces Dead Master, a girl carrying a jet-black scythe, in a fight to the death. The two fighters share a bond much like Mato and Yomi's, and Yomi's disappearance may be tied to the star charm and the gunslinger herself. The single OVA mixes school-life drama with action.