As Japan struggles with the most severe nuclear crisis in a quarter-century, publishers in that country are releasing books about nuclear power at the rate of more than one a day, according to bookselling Web sites. The Post’s Chico Harlan, reporting from Tokyo, writes that publishers are begging for content from authors who once wondered why they had so few readers. The hunger for material signals a sharp shift in Japan, as Harlan notes, “of a fringe interest turning mainstream.”