Prior to the beginning of the series, Strength encountered Black★Rock Shooter and the two of them fought purely on instinct. While they were fighting, Strength was pushed back and fell off a cliff behind her. She nearly died from the fall, but then she heard Yuu Koutari's voice, allowing her to feel emotions for the first time and sense how much Yuu was truly suffering. Knowing that she could take Yuu's pain with her if she were to die, Strength planned to let Black★Rock Shooter kill her so Yuu could forget her pain. Strength found Black★Rock Shooter mercilessly slaughtering other selves, but she did not go through with her plan and left without being noticed.