Most merchants do not accept dollars, and U.S. credit cards are not generally accepted outside of metropolitan areas or in small establishments.
Many Japanese products are considerably more expensive than American goods.
Host nation currency should only be exchanged at banks and other authorized exchange offices, of which there are many in Japan. Japanese currency is illustrated above. At most Japanese drinking establishments, one pays by the hour, not by the drink, and a cover charge is often included. Beer, juice and soda are also normally available. These are not normally free, but you will get them and pay for them whether you want them or not.