My hero!

A man in a white shirt grabs and lifts a man in a blue and white polo shirt in a dark alley, then the scene cuts to a girl in a school uniform turning to look at the camera, followed by a close-up of a handwritten note in Korean, then the girl and the man walking down a school hallway, then the girl looking up with a pained expression, and finally the man and girl standing face-to-face in a classroom.