But there are probably a large number of buyers who do not really possess the basic English skills to understand his speech, said Yuzo Yamamoto, an editor at Asahi Press. Since the sales took off, he has received postcards from readers saying they had been touched by Mr. Obama’s speeches, but “those same people have said they were moved even though they didn’t understand English well,” he said. “Some even said the only phrase they caught was, ‘Yes, we can.’ They said they were in tears nonetheless.”

Image A CD of President Barack Obama's inaugural speech has sold a half million copies in Japan, leading publishers to flood the market with over a dozen language-learning titles centered on his oratory. Credit... Miki Tanikawa

Mr. Yamamoto said there was a sincerity about Mr. Obama’s speaking style that listeners could perceive phonetically, combined with a delivery that was almost musical.

“That seems to result in sensation, the kind of which you get from listening to good music,” he said.

Other observers say that Japanese buyers probably feel as though they understand his speeches just from the nonverbal cues.

“The audience in the background helped too,” Professor Nikaido said. “The audience’s echo in the background works the same way as, say, laugh sound effects inserted in TV comedies.”

That may explain why Ms. Sakai, the beautician, and her customers were so enthralled by Mr. Obama. Ms. Sakai describes her English skills as less than perfect and says she relies on others for translation when she travels overseas. But when she hears Mr. Obama talk, she feels perfectly at ease.