The yoga teacher is Su-yeon Cha.
The two people on the left of this photo are Serina Liu and Zhao Enji.
The two on the right of this picture are: Hye-na Kim and Han-byeol Park (because they are too small, they only look more like Han-byeol Park in appearance).
Therefore, according to this inference, the one wearing flowery clothes in the middle should be: Huang Shengen.