The series arc has a narrative explaining Dong-eun's carefully crafted and long prepared revenge against Yeon-jin for her horrific bullying. There is a scene in episode 1 of Dong-eun confronting Yeon-jin in Dong-eun's apartment. This sets up the backstory of what led them to this point with Dong-eun's justification.
The only problem is this scene doesn't seem to fit anywhere in the actual story.
In a much later episode Yeon-jin breaks into Dong-eun's apartment and sees the photos. Dong-eun sarcastically remarks on it to her. But in that original scene Yeon-jin acts like she is seeing the photos for the first scene. Does that mean it was imagined?
I rewatched the first episode because the