"The society that leaves such problems unchecked could become one that is insensitive," Nakano said. "People gradually lose sensitivity and then think nothing of it anymore."
One word that has drawn attention is "leftist," which is being used as a catch-all term for liberals supportive of minority rights and pacifism, and who sometimes challenge conservative values.
The media and the political opposition are taking Abe to task for using the term too casually. Abe has also called former Prime Minister Naoto Kan a leftist, criticizing his civil activist background and relatively lenient stance toward North Korea.
Abe, who is known for his nationalist and hawkish views, complained in a recent Facebook entry about hecklers at a public rally. "A group of leftists came into the crowd, intensely trying to interfere with my speech by shouting into a loudspeaker and banging drums, full of hatred," he wrote
"Mr. Abe, what do you mean by 'leftists?'" asked Hideo Matsushita, senior editor at the liberal-leaning Asahi newspaper, in a commentary published Sunday.
Many of the hundreds of comments attached to Abe's Facebook entry expressed support for his remark, along with hatred of the political left, ethnic Koreans and China. But others questioned for using the word "leftists" to describe hecklers who were apparently opposing Abe's plans to join a U.S.-led trans-Pacific trade bloc.
Matsushita said Abe showed a lack of respect for dissent and was fanning animosity toward Japan's neighbors and ethnic minorities.
"What's the point of making a distinction between the left and the right?" he asked.
Since taking office in December, Abe has mainly focused on the economy. But his wider agenda includes revising Japan's pacifist constitution to allow a stronger military and building what he calls a "beautiful country" through patriotic education, traditional family values and respect for the emperor. Some critics say his plans harken back to the militaristic atmosphere prevailing before and during World War II.
The emergence of Hashimoto's Japan Restoration Party and the Liberal Democrats' victory in December elections is seen by many in Japan as a swing to the right that has been accompanied by verbal attacks on Japan's sizable ethnic Korean minority both on the Internet and in street protests, where members of ultra-rightist groups have shouted threats like "Kill Koreans" and "Go back to Korea."
Hundreds of thousands of Koreans comprise Japan's largest ethnic minority group. Many are descendants of workers shipped to Japan during its 1910-1945 colonial rule of Korea. Decades later, they still face widespread discrimination in education, business and marriage.
Anti-Korean sentiments have prompted a group of lawmakers and experts to propose excluding "hate speech" from the constitutionally guaranteed right to freedom of expression.
"These problems underscore Japan's lack of human rights awareness, and the world is raising its eyebrows," said Kazuko Ito, a lawyer who heads Japan's branch of Human Rights Now.
AP writer Elaine Kurtenbach contributed to this report.