Matsubara, Kaoru also know to her alter ego as Powered Buttercup, is the fighter of The Powerpuff Girls Z and also one of the main characters. She is originated from the show called the Powerpuff Girls and been adopted by the Japanese animation production, Toei Animation. The original creators of the characters and the show  is Craig McCracken. From the The Powerpuff Girls Z, She is represented as a Star and her weapon is a Hammer.

She is a tomboy and is the most easily enraged of the three, but she is sometimes more of a brain operator than her leader, Blossom.

She seems to dislike the Powerpuff clothes but she doesn't have any choice but to wear it to fight the bad villains, but it seems she enjoys kicking butt but not when she's tired. Kaoru is known at school for being the most athletic girl as she plays tennis, practices martial arts, and numerous other activities, and spends a great deal of time watching sports on television. She is especially good at soccer due to her strengthened determination after receiving new soccer cleats when she was younger. This may be part of the reason why she has so many fan girls, much to her dismay. She detests anything girly, particular skirts, which makes wearing the Powerpuff uniform a bit more awkward. She speaks with a hard and masculine edge and rarely uses honorifics when speaking. Kaoru lives with her Parents and her two brothers, the father of which is a professional masked-wrestler.