Kyösuke Hyöbu, a powerful esper criminal much older than he looks, briefly appears before The Children and at B.A.B.E.L. which brings the chief and Minamoto to go to the maximum security prison for espers where he should be, just to find that he was not restrained at all and could easily leave his cell and return undetected. Soon a rebellion breaks out at the prison and The Children confront the inmates to prevent them from escaping.