Japanese gate agents (and almost every station has one) are usually very cool about it though: they'll ask where you came from and how much you paid, and most o

Japanese gate agents (and almost every station has one) are usually very cool about it though: they'll ask where you came from and how much you paid, and most of the time will just trust you and charge you the difference or at worst just the price of the ticket. I've lost tons of tickets and have never been charged anything near the maximum price. [Looking like a foreigner is also probably a benefit in this situation, as they'll assume you don't know the system well, and additionally don't want the hassle of arguing with you.] That's one of my (many) reservations about POP ticketing (which is the darling of many transit advocates): there's a non-trivial chance of losing a ticket, and ending up paying very, very, dearly for a common honest mistake (typical POP fines for being caught without a ticket tend to be hundreds of dollars)...