Astro Boy is set in the near future, where robotic technology has become so advanced that it is threatening to radically transform human culture. Not only has the loss of many human jobs to robots led to social upheaval, but the robots themselves have become so sophisticated that mankind must begin to recognize them as another sentient species. In Astro Boy, Tezuka uses robots as an allegory to explore issues of prejudice and racial intolerance. The robots (and the humans who support them) often face a fierce political and social struggle to secure robot rights against humans who, fearful of change, often offer violent resistance. However, possessing the world’s most sophisticated and human-like computer brain, Astro Boy serves as a bridge between humans and robots, fighting to defend both races and establish peace and friendship between them.

(Source: http://tezukainenglish.com/)