1x07 Episode 7

I just hope Dan Sol read all of the shaman soul memories and just her current past ! There must have a reason she cried.

After watching so many eps, it seems more like Sang un's twin sis was the bulgasal and she passed it on to Eul tae. There was one part Hwal mentioned the monster was pretending to be a lil girl or something. Coz the only reason why Eul tae is connected to Sang un's pain is coz the bulgasal was transferred to him when he killed the sister. Just like how they always say twins are connected in some ways, that would explain the pain he's going through.