The former president of Peru, Alberto K. Fujimori, who is fighting extradition to Peru on human rights and corruption charges, may run for a seat in Japan’s legislative elections, his spokesman said. Mr. Fujimori, who has Japanese citizenship, has been approached by a small opposition party to compete in the upper house election next month, but critics called the move a ploy to avoid extradition to Peru from neighboring Chile, where he is under house arrest. Mr. Fujimori, 68, was arrested in Chile in November 2005 when he arrived unexpectedly from Japan, apparently in a bid for a political comeback in Peru. He had sought exile in Japan, the country of his parents’ birth, after his government collapsed under the weight of a huge corruption scandal.