In Japan you come of age at 20 years old.
It is a national holiday, called 成人の日/Seijin no Hi.
That’s the age at which you can drink, smoke and vote.
It’s held on the second Monday of January.
They gather in their home town if their 20th birthday is between April of last year and April 1st of the current year.
Men and women both wear special clothes for the event.
Women wear a special kimono called a furisode and men wear the hakama, but more recently suits have become popular.