According to a representative from SBS, the 4 members - Irene, Wendy, Seulgi, and Yeri - attended the recording for the show on February 6. Joy was unable to join due to filming for her new drama 'The Liar and His Lover'.
Currently, 'Running Man' is having 'Member's Week', where each member is creating a special of their own. However, 'Member's Week' will be taking a break on the upcoming episode for Red Velvet's surprise appearance.
The episode with Red Velvet will be airing on February 12.