Well, being away from your home and in a foreign country, sometimes is needed to go to restaurants, and if you have friends there, you might want to go to bars or other places for some kind of social interactivity, and if you ask me what do I like to do for this, I will answer you easily, I LOVE to go out to eat.

There are a few restaurants in Japan that have buffette, other only the menu, but one of my favourites are the ones that have this sign outside:

食べ放題 - Tabehoudai

What's tabehoudai? Easy: Eat all you want for the same price. There are many of these restaurants in Japan that offer this service, especially Yakiniku (焼肉), and well, as I said before, you can eat whatever you want and as much as you want paying only once. Generally, beverages are paid apart and you get a time limit to finish, usually between 1 or 2 hours, really convenient

There are also some restaurants and bars that have this sign:

土足のまま入って下さい - Dosoku no mama haitte kudasai

It means "Please enter with your shoes on" or "Is not necessary to take off your shoes to enter". Sometimes, for being so much time in that country, you get used so much to taking off your shoes everywhere that you begin to do it thoughtlessly. If you go to the dentist, some churches, many particular offices and some japanese-style restaurants, you get some slippers to enter (スリッパ - Surippa - Sandals to use inside the house), but there are many places where is not necessary to take off your shoes and sometimes you get confused because there are places (the mentioned before) in which you don't know if you should take off your shoes or not, there are even many japanese people that take them off when stepping inside the car, so I would also recommend you to ask before entering cars or places.

Also, there is the opposite side of the coin obviously:

土足禁止 - Dosoku Kinshi - Forbidden to enter with shoes

or

土足厳禁 - Dosoku Genkin - Strictly forbidden to enter (or step) with shoes on.