Reserved vs. non-reserved cars
Most shinkansen trains offer both non-reserved seats (自由席, jiyūseki) and reserved seats (指定席, shiteiseki) in separate cars. Only the Hayabusa, Hayate and Komachi trains along the Tohoku Shinkansen are fully reserved and carry no non-reserved seating. All seats in Green Cars are reserved. Bilingual signs indicate whether a shinkansen car carries reserved or non-reserved seats.
Advance seat reservations are required to use a seat in a reserved car (see below on how to make seat reservations). A fee of a few hundred yen applies for making seat reservations. Japan Rail Pass holders can make seat reservations for free.