Lost Property on Japan Trains: How to Recover a Bag or Phone
You step off a Shinkansen and realise that your bag is still above the seat. Or your phone is missing after a subway transfer, and you cannot tell whether it stayed on the train or fell near a ticket gate. Japan has organised lost-property systems, but there is no single desk for every railway. The useful first move is to identify the operator, preserve the journey details, and make a report that staff can actually search.