Complete Breeding: The Aesthetics of Confinement (2018)

Eun-hee and Jung-yeon head toward a pension to have a blast with the guys. Chul-soon is the janitor and he is caught sneeking a peek at Eun-hee and Jung-yeon tanning, but gets away with it in return for letting them take an embarassing video of him. That night, while having dinner, Eun-hee excuses herself from the table and Jung-yeon and Min-ki have sex. They realize someone is wwatching and thinking it's Chul-soon again, beat him up. However, Chul-soon is innocent and he decides to take revenge.