Jeong Seong-Min hands are tied up & Lee Ha-Yeong is giving him blowjob from behind while, he is in doggy position. They are seeing, Live feed of Choi manipulating Sin Ah, as Sin Ah kisses Choi on her own.
Not to be confused with the 'doppelganger Kim Min-seong' which is actually Jack Choi from sex scenes chapters 68-69 & 72-74. This sex scene (chapter 71) is the 'real' Kim Min-seong who was tied up on chair which is Ha Lina's husband.
Song Saetbyul
