Ms. Keane is the schoolteacher who teaches the girls in The Powerpuff Girls.
She teaches Blossom, Bubbles, and Buttercup at Pokey Oaks Kindergarten. Ms. Keane is generally patient and caring, but she also expects the girls to follow classroom rules and behave like ordinary students despite their extraordinary abilities.
The school stories provide a recurring contrast with the action plots. The girls may be able to fly, fight monsters, and stop disasters, yet they still face lessons, social problems, and the responsibilities of being young children.
Ms. Keane is not the same character as Sara Bellum, who assists the Mayor at Townsville City Hall. The two women are both recurring adult characters, but they have entirely different jobs and settings.