Akane tries to get to know her quiet classmate, Rei Kuroki, unaware that she is the one assisting the Alone. As Akane decides to follow Rei after school, she sees her save a child from a falling piece of construction. As Rei returns home, she is visited by a crow, who punishes her for saving the child via a mark on her neck, reminding her of her mission. That night, Rei goes on a mission to destroy the Manifestation Engine by herself, but is forced to abort when she is discovered by patrol robots. The next morning, Akane finds her washed up on the shore and takes her back to her place to help her recover...