Chippo-kun Konnichiwa

Cats are supposed to catch mice and eat them. However, Little Chippo, the boy kitten, revolted against this common practice in cat society. He would neither eat mice nor could he imagine eating one. He knew that he would rather run away from his parents than be forced to eat a mouse. So he was expelled from cat society, and started to live with the mice. Then he gradually gained trust in the mouse world as a guardian of mice.

(Source: Tezuka Osamu Official)

Note: The entry reflects the manga version; it does not count the two picture book versions included in the volume.