At 45, Yukio Mishima was the outstanding Japanese writer of his generation, celebrated both at home and abroad for his plays and novels, including Confessions of a Mask, The Temple of the Golden Pavilion, and The Sailor Who Fell from Grace with the Sea. In 1970 he startled the world by stepping out onto a balcony in Tokyo before an assembly of troops and plunging a sword into his abdomen; a disciple then beheaded him, completing the ritual of hara-kiri.<BR>John Nathan's biography traces the life of this tortured, nearly superhuman personality. Mishima survived a grotesque childhood, and subsequently his sadomasochistic impulses became manifest - as did an increasing obsession with death as the supreme beauty. Nathan, who knew Mishima professionally and personally, interviewed family, colleagues, and friends to unmask the various - often seemingly contradictory - personae of the genius who felt called by "a glittering destiny no ordinary man would be permitted."