Japan’s Mitsubishi Motors Corp has started preparing for the closure of its sole U.S. factory after failing to find a buyer for the high-cost auto plant, the Nikkei business daily reported on Saturday. The 900 hourly workers at the Normal, Illinois plant are the only ones at a Japanese-owned U.S. auto factory to be represented by the United Auto Workers (UAW) union. Mitsubishi Motors could not immediately be reached for comment.