Popular K-pop boy band JYJ on Thursday began a massive annual festival in Seoul for its local and Japanese fan clubs.

The trio has held the "JYJ Membership Week" festival annually in the capital city for free since 2012 to better communicate with their fans, drawing more than 20,000 people each year from home and abroad.

This year's event, the third of its kind, is scheduled to last until Sunday at the COEX convention center in southern Seoul, according to C-Jes Entertainment, which manages the band.

Themed "All about JYJ music," the festival is composed of an expo, a meeting with fans and a showcase of the band's hit songs.

Admission is free to all members of the management agency but the "fan meeting" event is available only to a small number of randomly chosen members.

"We made efforts to make our fans feel as if they are together with us and have fun, rather than a space that can arouse their astonishment," Kim Jae-joong, a member of the trio, said.

Another of the team's members, Park Yoo-chun, expressed thanks to their fans for coming to the annual festival, making it possible for the group to open such an event every year. "We wanted to give our fans as diverse presents as possible," he said.

In the expo, visitors can see videos and photos as well as some 600 stage costumes of the group and a miniature set from the filming of the video of the group's latest album, the company said.

A documentary film about how the trio is getting along these days is also part of the expo.

About 20,000 randomly chosen fan club members, including 4,000 from Japan, are expected to attend the free event, the agency said. (Yonhap)