Her overconfidence manifesting itself as frequently as her chewing gum bubbles.
Setsuko was once a B.A.B.E.L. agent who had a bitter one-sided rivalry over popularity with the younger and more affectionate Naomi Umegae as they serve in same period during their teens. Losing the battle and became bored with the work as a Special Esper and sought greater excitement and euphoria. Considering how she thoroughly enjoyed all the headaches her subterfuge is causing B.A.B.E.L. when Hyōbu charges cerebral subjugation of Minamoto to use as a coercion device on Kaoru, it seems that P.A.N.D.R.A. meets this necessity for Setsuko.
Setsuko is a very minor character in "Zettai Karen Children: The Unlimited", mostly getting relegated to the background.
Her power is based on telepathy and she uses it to manipulate dreams in order to create a dream world within the minds of others. With a click of her camera shutter, Setsuko easily sends her victims into cerebral pseudo-realities of her own custom design that are very difficult to reverse.