In Japanese restaurants, when you enter the restaurant and take a seat, you will probably be given a small wet towel by the waiter. You may also find it on the table. This is called an oshibori, and it is offered as a part of the culture of hospitality in Japan so that you can wipe your hands before eating and enjoy your meal with clean hands.
Oshibori can be either made of cloth like a towel, or paper. When you buy a bento (boxed lunch) at a convenience store, a paper-type oshibori is sometimes included free of charge.
Oshibori are used to wipe your hands, and it is considered bad manners to wipe any part of your body other than your hands in a restaurant. Moreover, please leave your used hand towel on the table. If there is a trash can, you may dispose of the paper type in the trash by yourself.
