A national media exerts a powerful influence over the lives of members of its society. For example, rumors or untruths disseminated through print or broadcast can destroy livelihoods and leave reputations in ruins.
This is why judiciaries provide mechanisms to keep media accountable. In Japan, laws against libel and slander exist to punish those who put out misleading or false information about individuals.
But what about broadcasting misleading or false information about groups? That's a different issue, because Japan has no laws against "hate speech" (ken'o hatsugen). Consequently, Japanese media get away with routine pigeonholing and stereotyping of people by nationality and social origin.