The most common eye color in Japan is brown, with an estimated 80% of the population having brown eyes. Black is the second most common eye color, followed by blue, green, and gray, which are considered rare in Japan. While genetics play a major role in determining eye color, environmental factors can also have an impact. In recent years, there has been a trend among Japanese people to wear colored contact lenses to change the color of their eyes, influenced by Western media and fashion trends. However, it is important to remember that eye color does not define a person's identity or worth.