Japan is famous for its "fast food" - the food bar (that's what I'm gonna call it from now on).
How do you order from these kinda bars? Well, its easy. At the entrance of this place, there's always the menu.
Pick what you want. Though, not all of it comes with English words.
Since its the land of the vending machines - there's this vending machine at the entrance. You place your money in it, and pick the food that you want. If you're lucky, you get the pictures there (and if you're even luckier - it'll be in English!). Otherwise, it'll be just Japanese words, and you'll have to randomly pick out something to eat. Hopefully its something edible.
Then you get your ticket. Walk into the bar - sit at the stools (but some places there's no stools - you'll have to stand!), and give the ticket to the person behind the bar.
Then comes your food! Usually water or tea is for free.