Some places don't have a cashier, just a ticket machine.
We'll go for dinner at one of these after checking into our hotel the first night in Japan.
This one even has pictures of the dishes on the buttons. Not all of them do.

There's also the usual window full of plastic models of the food the restaurant serves.
In front of each dish, there's a card with the name and price of the dish.
In Japanese.

Memorize at least the price and some important feature of the kanji/hiragana/katakana if you can't actually read it.
Or take a picture with your phone or digital camera.

When you go inside, you'll need to find what you want to eat listed on those buttons, put your money in the slot and be sure to push the RIGHT button.

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