Ami Koshimizu
In an interview reported by the anime magazine Newtype USA, seiyu Ami Koshimizu talked about the difficulty of voicing Kallen because of the double life that her character leads. Certain aspects of Kallen's character such as her girlish naivete and competitiveness made it easy for the voice actress to relate, even to the point of admitting that in some ways they act very much the same.