Instructions
Search the face of the coins for any obvious signs of the country of origin. Many coins, especially modern coins, have certain inscriptions in English, and if any of these tell you the coins' country of origin, you are already done.
Look for any other words that you can decipher. If the words rin, sen or yen appear in English on either face of the coins, you have a Japanese coin. Unfortunately, not all Japanese coins are marked in English.
Search the faces of the coins for Japanese-looking characters. If no exotic characters exist, your coin is unlikely to be Japanese. Even if Japanese-like characters are present on the face of the coin, you will still need to do some research to decide if your coin is Japanese or not.
Examine the images on the coins. Japanese coins often have pictures of the sun, dragons, traditional Japanese architecture and flowers on the faces of the coins. Japan also minted several different varieties of coins with a hole in the middle. While this is not a definite sign that your coin is Japanese, it can help to identify your coin.
Take your coins to a dealer who works with Japanese coinage if you still cannot tell if your coin is Japanese. They will be able to tell you what type of coin that you have and how much it is worth. If no coin dealers in your area have expertise in Japanese coins, several books and price guides have been published that would help you identify your coins.