With this popularity, reserving seats on the Shinkansen ahead of time is a common practice. This is especially recommended during peak travel times, such as Spring, Fall, and New Years, and not just for bullet trains, but for some Express Trains as well.

Whether you need to reserve a Shinkansen seat in 2026 depends on the train type and the time of year. For the fastest trains like the Nozomi on the Tokaido/Sanyo lines, all seats are now mandatory-reserved during peak holiday periods (New Year, Golden Week, and Obon). Outside of these peaks, you can often use "Non-Reserved" cars (usually cars 1–3) without a reservation. However, certain high-speed services like the Hayabusa (to Hokkaido) and Kagayaki (to Kanazawa) are "Reserved Only" year-round, meaning you cannot board without a specific seat assignment. It is a peer-to-peer recommendation to book in advance via the SmartEX app or at a "Midori-no-madoguchi" ticket office, especially if you are traveling with large luggage, as specific "oversized baggage" seats are required for bags with total dimensions over 160cm. Reserving provides peace of mind and ensures you won't have to stand in the aisles on a busy two-hour journey between Tokyo and Osaka.