GaIn was a prostitute working under the Aussie pimp. She was assigned to attract the guy in the MV but they didn't know he was a killer or something like that. You see GaIn expressing fear as she hurriedly locked the door of the car. They became lovers in time but the guy felt that he might one day kill her or hurt her so he decided to go away. GaIn didn't understand and wanted him to kill her instead. He dies in the end as he offered himself instead of GaIn dying Gain locked the car door bc she thought the man was going to tell the pimp that she want to escape, far away from the pimp. But he came back with blood on his sleeves --> maybe he had killed the pimp and set Gain free. He set her up but he didnt want her to live in his dangerous life (he's a dude) so he told her to find the bag (with money inside) and went away from her. But all she wanted was being with him...