In 2026, it is relatively rare for Shinkansen (bullet train) tickets to be completely "sold out" because trains run so frequently, but reserved seats on popular routes like the Tokaido Shinkansen (Tokyo to Osaka) absolutely sell out during peak periods. High-demand times include the Golden Week (late April/early May), Obon (mid-August), and the New Year holidays. During these windows, if you do not book in advance, you may be forced to stand in the "Non-Reserved" cars, which can be extremely crowded. Additionally, the newer "Smart EX" booking system and the recent price hikes for the JR Pass have changed how tourists secure seats; many now book weeks ahead via the app. For travelers with oversized luggage, the oversized baggage area seats are limited and almost always sell out first. While you can usually find a seat on a train eventually by waiting for the next departure, booking at least a few days in advance is highly recommended to ensure you get your preferred time and a guaranteed seat for a comfortable journey.