To find out if you go on vacation to Japan for the first time this summer, some restaurants (mostly chains), make available to their customers a buzzer on the table to call a server. Neither one nor two, as soon as you sound, your server turns up pronto order book (or rather the touch pad) hand.
Always useful to know if you have not spotted the famous buzzer and do not understand why nobody comes to see you (yes perfectly, it's live!).
