[source : https://www.keioplaza.com/keywords/seijin.html]
Coming of Age Day, which is called as seijin-no-hi(成人の日) in Japanese, is a national holiday in Japan. Every year, Japanese people who have just turned into 20 years old or will soon celebrate this special day in a life on second Monday of January. Many countries have their own way to celebrate Coming of Age Day; for example, in some countries people give perfume and flower to a person who became certain age. It is also possible that nobody celebrates this day in some nations.