Yes, Pasmo card funds expire if the card is not used for 10 consecutive years. This 10-year rule applies to most Japanese IC cards, including Suica and Icoca. The "clock" resets every time you use the card to pass through a ticket gate, make a purchase at a convenience store, or add funds at a recharging machine. If your card does expire due to a decade of inactivity, the balance becomes invalid. However, if you return to Japan after a long absence, you can often take your expired card to a station office (Midori no Madoguchi); while the physical card might be decommissioned, staff can sometimes transfer the balance to a new card or provide a refund, although a small handling fee (typically around 220 yen) may apply. To avoid expiration, it is recommended to use your card at least once during your trip for a small purchase, such as a bottle of tea from a station vending machine.