Japan Shuts Citigroup Private Bank Unit  TOKYO/NEW YORK (Reuters) - Japan on Friday ordered  Citigroup Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=C.N target=/stocks/quickinfo/fullquote"&gt;C.N&lt;/A&gt; to close its Japanese private banking  offices after uncovering a series of problems, including a  failure to prevent suspected money laundering.