Depending on how the airport is laid out, the immigration procedures for passengers on business jet aircraft is usually the same as the procedures for general airline passengers. For instance, it takes about 45 minutes to clear customs and get to the exit after a business aircraft lands at Narita Airport. When departing, it is advisable to arrive at the airport 45 minutes before departure time in order to proceed smoothly to your aircraft.
UTC (Coordinated Universal Time) or Z is added to World Standard Time. Simply add 9 hours to World Standard Time to determine Japan Standard Time.