There is the actress/model Park Han Byul who is the longtime girlfriend of Se7en. Both she and Se7en (Choi Dong-wook) are good friends of RAIN. Se7en began his military service recently and he and RAIN are serving together in the South Korean military's PR unit.
The other Byul is Kim Go-Eun. Byul is her stage name. Her "I Think I" song is part of the soundtrack for RAIN's Full House drama.
Byul was RAIN's opening act in China in the Rainy Day tour of 2005.
She married singer/actor/comedian HaHa (Ha Dong-hoon) on November 30, 2012 and currently is expecting her first child late this summer of 2013.
Before Byul was known for "I Think I" and before she married HaHa, there was already a RAIN connection. HaHa was one of the hosts of "What's Up Yo". RAIN appeared several times on it. Here are two of his appearances:
2002.08.14 (August 14, 2002)
Talk portions of this show can be viewed at youku:
part 1 - http://v.youku.com/v_show/id_XODM1NTY3MzY=.html
part 2 - http://v.youku.com/v_show/id_XODM1NjU2NzI=.html
2004.01.28 (January 28, 2004)
Byul's "I Think I" was originally released on her 2nd album, Star, in 2005. Her debut album, December 32nd, was released in 2002 and contained a duet entitled "How Much I Love You"sung by Byul featuring RAIN. Enjoy hearing it here:
In a matter of only a few days our very own World Star RAIN will return!