On the Japanese Shinkansen, each passenger is generally allowed to carry up to two pieces of luggage, provided they do not exceed a combined weight of 60kg and the total dimensions (length + width + height) of each bag do not exceed 250cm. However, as of 2026, strict rules apply to "Oversized Baggage" (bags with total dimensions between 160cm and 250cm). If you have a bag in this size range, you must reserve a specific "seat with an oversized baggage area" in advance. This reservation is free if booked with your ticket, but if you board without a reservation, you will be charged a 1,000 yen penalty and may be asked to move your bag. Most standard "international size" suitcases fall into the oversized category. Small carry-ons and medium suitcases that fit on the overhead racks do not require a reservation. These rules are strictly enforced on the Tokaido, Sanyo, and Kyushu lines to ensure the aisles remain clear and the trains maintain their legendary punctuality and safety standards.