Interfaith Days: January 12th, Seijin no Hi

from: http://www.tuvy.com/blog/2010/08/shinto/

In the Shinto faith, today is Coming of Age day, or Seijin no Hi. Coming of age festivals have been held in Japan since the 8th century, but this particular day was established during the 20th century for January 15, and then the day was set at the second Monday of January. The day congratulates people who have reached the age of 20 and thus are recognized as adults. Festivals, ceremonies, and parties mark the day.

(From the 2015 Interfaith Calendar of the Diversity Awareness Partnership of St. Louis---see dapstl.org for more information---and various online sources.)