More than 1.2 million young people in Japan spent Monday dressing up, riding roller coasters and drinking alcohol as they participated in the country's annual Coming of Age Day festivities. Coming of Age Day, held every year on the second Monday in January, is a national holiday that honors the country's newest adults, aka everyone who turned 20 over the past year.

"I’m very nervous," Rumiko Matsumoto, a college student, told Agence France-Presse. "It’s a special day, the first step towards being an adult. My parents told me I have to take responsibility for my own actions now. But first I want to celebrate by going drinking."

Coming of Age Day is a tradition that dates back to the 700s, though it only became official in the 1940s. Whereas initially young adults would cut their hair and dye their teeth black for the holiday, according to Kids Web Japan, people these days honor the transition to adulthood by dressing in expensive furisode and kimono outfits, taking part in serious ceremonies, having family parties, dancing in the streets and going clubbing with friends. They also legally smoke and drink.

Everyone who turned 20 during the previous academic year — April to April — is invited to the festivities, according to Stars and Stripes Okinawa. But Coming of Age Day isn't just reserved for partying — people also must prepare to change their lifestyle and contribute to society.

"The purpose of this holiday is to congratulate and encourage young men and women who attain the legal age of adulthood to fulfill their new-found responsibilities and become self-reliant members of society," Masahiko Uchino, a public official with Japan's cabinet office, told Stripes Okinawa.

In recent years, Coming of Age Day bashes have taken on an even more serious tone as its population has aged. In 1970, 2.46 million young adults were eligible to celebrate, but in 2014 only 1.2 million were, Quartz reported. Monday's holiday saw a slight uptick in participation from last year's record low amount, according to the Mainichi.

See photos of Monday's gaiety below:

RTX2Y2G6 Japanese women wearing kimonos attend their Coming of Age Day celebration ceremony at an amusement park in Tokyo on Jan. 9, 2017. Photo: Reuters

RTX2Y2ED Japanese women wearing kimonos take a 'selfie' after their Coming of Age Day celebration ceremony at an amusement park in Tokyo on Jan. 9, 2017. Photo: Reuters

RTX2Y2EE Attendants hang around before their Coming of Age Day celebration ceremony at an amusement park in Tokyo on Jan. 9, 2017. Photo: Reuters

RTX2Y2D1 Japanese women wearing kimonos ride a roller coaster during their Coming of Age Day celebration ceremony at an amusement park in Tokyo on Jan. 9, 2017. Photo: Reuters