With Coming-of-Age Day taking place Monday, the city of Kitakyushu has an important message for the attendees: Dress fittingly.

The city says it is tired of seeing what has become a common occurrence at the annual event — new adults dressing inappropriately, spoiling the solemn atmosphere.

In recent years, Kitakyushu's Coming-of-Age Day ceremonies have been marked by young men wearing vividly colored hakama, a trouser component of the kimono, making them look like hooligans to some.

A number of them also wave flags as they drive around in convertibles to celebrate.

The new women meanwhile are starting to wear a looser-fitting style of kimono that exposes the shoulders in a way used by oiran, the high-class prostitutes of the Edo Period.

"The coming-of-age ceremony is supposed to be a serious event where you demonstrate your recognition that you have become an independent adult," said Kitakyushu official Yasuhiro Iida.

Fed up with the trends, the city has taken the unprecedented step of setting up a website to educate new 20-year-olds on appropriate attire for the event.

The website, launched last November, followed mounting complaints about inappropriate attire, Iida said.

Groups of fledgling adults erupting into drunken frenzies and sabotaging the events have nearly become synonymous with TV coverage of the holiday in some parts of the nation.

But not all of them are that way. Some put on showy attire and often "turn raucous," but they don't necessarily disturb the ceremony itself by vandalizing property or getting into fights, Iida said.

Instead, they show good sense by skipping the event altogether and meet up in a nearby park, he said.