K-pop boy band JYJ, whose members departed TVXQ in 2009, brought some nostalgia to fans by performing a TVXQ song at a concert in Japan.

JYJ members Jaejoong, Yoochun and Junsu -- the three former members of TVXQ -- performed “Begin,” from TVXQ’s sixth Japanese EP, at the end of the concert in Tokyo, Japan, Tuesday.

JYJ (C-JeS Entertainment)

The trio revealed why they chose to perform the song at a press conference the next day, ahead of another show.

“’Begin’ tells of how we feel about our fans. We wanted to present our fans with a nostalgic song that can send our message,” Junsu said.

“Begin” was released in Japan when then-quintet TVXQ were at the peak of their popularity.

Junsu (OSEN)

Junsu said that he wanted to sing the song onstage but did not have a chance until recently.

In fact, JYJ regained the right to perform the track only recently, after winning a legal battle with SM Entertainment, the label the members were signed to as part of TVXQ. The boys filed a lawsuit against SM in mid-2009, alleging their 13-year exclusive contract was unreasonably long.

The trio is currently touring Japanese cities for the “2014 JYJ Japan Dome Tour.” They recently wrapped up their second concert in Tokyo on Wednesday, drawing a total of 100,000 fans to the two shows. The boys will perform again in Osaka on Dec. 13 and 14 and Fukuoka on Dec. 23 and 24.

By Ock Hyun-ju (laeticia.ock@heradcorp.com)