She's no other than HyoYeon, and here's her group picture together with SeoHyun and the cast of the musical~
Following that, SeoHyun and HyoYeon also recorded a cute clip.
SeoHyun with her cast member
Release Date: February 28, 2017
Release Date: January 17, 2017
Release Date: June 28, 2016
Release Date: December 10, 2016