Whenever I've used the Tokyo Metro subway system, I've always paid cash, so using IC cards is not "familiar territory" for me.
But, I've learned a little something about them from an article in the Tokyo Reporter.
TOKYO (TR) – A word of warning to commuters on the Tokyo Metro subway system.
A 57-year-old woman working as a cleaner on the underground lines in Japan’s capital has been caught spending money from an IC card a passenger accidentally threw in the trash.
The card in question had around 3,100 yen remaining on it, which the woman spent on herself. Procedures on the Metro lines require cleaners to pass on anything of value found in the trash to their office.
IC cards in Japan include the names, addresses and phone numbers of their holders, meaning that the card — and the money on it — could have been returned easily.To read more, go here.