While you are not strictly required to purchase Narita Express (N'EX) tickets weeks in advance, it is highly recommended to book them before boarding because all seats are reserved. You cannot simply hop on with a standard IC card (like Suica or Pasmo) without a seat assignment. In 2026, many travelers use the JR-East Train Reservation website or the machines at the airport to secure a ticket upon arrival. If you are traveling during peak seasons like Golden Week, Cherry Blossom season, or New Year's, trains can sell out quickly, so booking a few days ahead provides peace of mind. Note that if you have a JR Pass, you still need to visit a ticket office or kiosk to "redeem" your free reservation for a specific seat before you can pass through the gates to the N'EX platforms.