Paris Hilton left Japan this morning after reportedly being denied entry into the country.  Paris left after undergoing lengthy questioning from airport officials after pleading guilty this week to cocaine possession.  The 29-year-old Hilton had flown into Tokyo on Tuesday for a fashion show.    Authorities in Japan can deny entry to anyone convicted of drug-related offenses.   On Monday, the 29-year-old hotel heiress pleaded guilty in a Nevada courtroom to charges of drug possession and obstructing an officer.