Burning (2018)

The truth is all in your head.

Deliveryman Jongsu is out on a job when he runs into Haemi, a girl who once lived in his neighbourhood. She asks if he'd mind looking after her cat while she's away on a trip to Africa. On her return, she introduces to Jongsu an enigmatic young man named Ben, who she met during her trip. One day Ben tells Jongsu about his most unusual hobby.