TOKYO—As Japan's nuclear crisis deepens, a gulf has developed in the way in which the foreign and Japanese media are covering the unfolding drama.

The disparity has led to a stark difference in public perceptions of the gravity of the situation: Many Japanese are going about their daily lives and routines as normal. In sharp contrast, many foreigners have left after being deluged with phone calls from relatives pleading them to leave Japan after watching and reading media reports in their home country.

"Japan...