Satsuriku no Tenshi EP16 - Stop Crying and Smile.

Gray shoots Danny again to prevent him from shooting Zack. As Zack carries Ray through the exit, Gray has a final conversation with Danny, revealing that he became fascinated with how Ray and Zack managed to change each other, and how he's come to realize that everybody is a human, both flawed and beautiful. The building then collapses, presumably killing both Danny and Gray. Zack is able to reach the surface just as the police arrive to investigate the building collapse, surrendering to the police so Ray can be taken to a hospital. After recovering from her wounds, Ray is taken to a mental care facility where the staff attempt to rehabilitate her with limited success. Deemed guilty for his murder spree as well as killing Ray's parents and kidnapping her, Ray is informed that Zack is sentenced to death. However, shortly after hearing the news, Zack breaks into Ray's room to fulfil their oath, having escaped prison. As they both leap out of the window to escape, Ray once again pleads for Zack to kill her, which Zack reaffirms by telling her to stop crying and smile. By the time the police arrive, the room is already empty with a splatter of blood on the windowsill and Zack's knife on the floor.