Complex sentence: Seiji Fujii wrote a novel about the case "17-sai" which turned manga Youji Kamata contrary to what had really happened, the novel shows a happy ending for the girl, who's still alive and her kidnappers are sentenced to jail for many years.
Split into simpler sentences: Seiji Fujii wrote a novel about the case "17-sai" which was turned into a manga by Youji Kamata. Contrary to what had really happened, the novel shows a happy ending for the girl, who's still alive and her kidnappers are sentenced to jail for many years.