Jack

Jack (ジャック, Jyakku) is a minor character in Black★Rock Shooter: Innocent Soul.

History
Jack was a young man who was obsessed with death and committed murders every full moon. He was eventually caught by the police after his eighty-seventh murder.

After getting executed for his crimes, Jack's soul neither ascends to heaven nor descends to hell, but lingers in the Threshold as a Stagnant Soul, where he creates an illusive town and traps the souls of his murder victims so he can murder them repeatedly and fulfill his murderous thirst.

When Rock investigates the town, she meets Leto and Io who reside there and befriends them. Io becomes Jack's fifty-fourth victim when she ventures out at night under the full moon to craft a floral wreath for Rock. Jack then fatally wounds Leto, who goes out to search for Io after noticing she is missing, and mocks him for forgetting their deaths in the past. When Rock arrives at the scene, Jack mistakes Rock as one of the unregistered victims, but soon realizes that she is actually a Black Star - entities who hunt Stagnant Souls. He is no match to Rock and her partner Ron's attacks, and is swiftly destroyed in a one-sided battle.