紅葉 (kōyō) refers to the beautiful phenomenon of autumn leaves changing color, primarily seen in deciduous trees. This transformation occurs as temperatures drop and daylight decreases, causing chlorophyll to break down and revealing vibrant hues of red, orange, and yellow. In Japan, 紅葉 is a significant cultural event, attracting many visitors to parks and mountains to enjoy the stunning scenery. Popular spots for viewing 紅葉 include Kyoto, Nikko, and Hakone, where the natural beauty is celebrated through festivals and traditional activities, making it a cherished part of the autumn season.