Popular firework shows tend to be very crowded which leads to a few concerns for visitors:
The competition for good viewing spots can be quite strong, and people often show up and reserve the best spots hours in advance, especially in cities where tall buildings limit the number of spots with unobstructed views of the fireworks. Many shows offer paid seating, but tickets are usually not available on the day and are often difficult to get from outside of Japan or without Japanese language skills.