(South Korea, dir: Jung Ji-Woo)
Dating app developer Kim Sum falls for serial killer Seong Yun-O, who uses her app to find lonely women and tell them exactly want they want to hear. One of these women is Kim Sum's estranged friend, a police officer. For some unfathomable reason, Yun-O lets her live, and while he and Kim Sum get closer, police girl and another friend start to investigate.
This one's a bit of a mess. I liked it.
Mild spoilers below the cut.
I should not have looked at the comments over at AsianWiki... People are currently complaining that the lead actors - THE ACTORS!!! - have a 9 year age gap. Humanity is doomed.