Don't listen to that fluffhead Risvik, he's mental that's all.
To say who Kaylee is, you first need to explain what she is. Kaylee is a rat, and also our sensei, whom brought us in and nurtured us as if we were her own, after we were flushed down the toilet. She taught us martial arts and warfare, and now we fight off the evil-doers of this city, Shredder and his companions.
Kaylee is Splinter.