The validity of a Japan Rail (JR) Pass is calculated based on consecutive calendar days, not 24-hour periods from the time of activation. When you exchange your "Exchange Order" for the actual pass at a JR office in Japan, you must specify a starting date. Once that date begins, the clock starts at midnight and the first day is counted. For example, if you have a 7-day pass and you activate it at 3:00 PM on a Monday, that Monday counts as Day 1 in its entirety. The pass will expire at exactly 11:59 PM on the following Sunday. It does not matter if you use the pass for only one hour on the first day; it still consumes a full calendar day of your allotment. This makes it strategically advantageous to start using your pass early in the morning on your first day of travel to maximize its value. If you are on a train when midnight strikes on the final day of your pass, the pass remains valid until you exit through the ticket gates of your final destination station, provided you boarded the train before the expiration time. This consecutive-day rule is why many travelers use local transport or IC cards for their first few days in a city before "triggering" their pass for long-distance Shinkansen travel.