Kasey is Blossom's ten-year-old sister, and she is just as hyper and addicted to the sentai/hero genre as her older sister. She is very independent and likes to pretend she is a heroine. She admires the Powerpuff Girls Z and wishes to be a heroine just like them. She admires Bubbles and Buttercup, but shows little favor for Blossom (who, unbeknownst to her, is actually her own sister). She is also always looking for new ways to annoy her sister. She appears to be quite interested in Ken, especially when she realizes that he knows her sister. Similarly, Ken seems interested in her because of her resemblance to Blossom.