TOKYO—In the words of Nobumasa Akiyama, a Tokyo academic and commentator, Japan is fed up after all these years with playing the role of a "good loser," the country that bowed its head after defeat in World War II and accepted a forever diminished status as a nation.

And that, he says, accounts in part for the spectacular domestic political success of Prime Minister Shinzo Abe, who is striving to remove a post-war stigma that hangs over a vanquished people tired of being apologetic for the past.

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