The K-9 Robot (K-9ロボット) is a robotic dog created by Senbei Norimaki for the purpose of tracking people by scent.
The Birth of Arale
Main article: Volume 1: The Birth of Arale
The K-9 Robot is invented in the chapter "Dr. Monster" as a way to locate Arale Norimaki after she ran off forgetting to refuel on Robovita-A. He tracks down Arale by using her scent from a pair of her panties with him question why he's sniffing a robot's underwear.