The Japanese ceremony held on the second Monday of January to celebrate young people reaching adulthood is called Seijin Shiki.
The ceremony is part of Coming of Age Day, or Seijin no Hi, a Japanese public holiday. People who turn 20 during the relevant period traditionally attend municipal ceremonies, often wearing formal suits or furisode kimono. The event commonly includes speeches by local officials and time for friends to gather.
Japan lowered the legal adulthood age from 20 to 18 in 2022, but the age used for many Coming of Age Day ceremonies remains 20. This distinction can cause confusion: legal adulthood and participation in the public celebration are no longer exactly the same.
Seijin Shiki is the modern civic counterpart to older Japanese rites such as genpuku, which marked elite boys’ transition to adulthood in earlier periods. It is therefore a contemporary national ceremony, not the historical rite itself.