Besides high-end restaurants, you don’t usually get an assigned server for your table in Japan. The processes of seating, communicating your order and receiving your meal may involve three different waiters in some cases. This difference (especially to many western countries) is probably based on the fact that there is practically no tipping culture in Japan, so it doesn’t matter whether or not a server is designated to a table.
Also, if you need to get your waiter’s attention, it is completely acceptable (and not considered rude) to raise your hand and call “sumimasen” (excuse me).
