the characters in this were really well developed, Kyung Mi was a normal fragile girl next door but that didn't mean she was not capable.
she was smart, she was scared and she was so sweet hearted honestly she was too precious!
Kyung Mi's mom was also smart, honestly most movies make the female characters too naive or dumb and easily fooled but both mother and daughter used their brains and they communicated.
there were small details in their relationship that made them so endearing and believable, like the mom pulling Kyung Mi behind her as if that tiny fragile older lady can "shield" her taller youthful daughter, but it was such a mom thing to do

Do Shik as a psychopath was so captivating, psychopath's lie and he did it so well, like the way he switched characters to fit the scenarios and make the public believe him and even get away with the murder he reported, that was a great move
it also made his downfall even more satisfying.

Jong Tak and his sister felt underdeveloped, tbh even that full long running sequence mixed with him getting fooled and leaving Kyung Mi the 1st time made me reduce my points because that was obviously a ploy for the length of the movie
it's not bad, like the movie happens in "one night", if not even around 4 hours. Kyung Mi and her mom met, the psychopath came in, they went to the station, he followed them home at around 12am


the saddest part was those army kids.. if you see a scared girl, you don't return her to the guy that's following her, even if he played it well and pretended to be her worried brother. heck I've helped lost kids at the mall find their parents and I still wait and check if that's their parents even if just by action, I'm not anticipating a kidnapping but when someone cries and can't talk, you need to observe the situation

I also loved those danger poles, I hope those are real, I've never seen a movie brave enough to add that especially since it can "solve" the chase. though in this case it added depth to the struggles of people with hearing impairment.
though I didn't like how people almost treated her like she's dumb or like a kid. she just couldn't hear or talk, there was no problems with her coherent thoughts
though it also does add the depth of how people treat "different" people

as for the "music" I really loved the times they showed how the world "looked" like from her silent pov, that was a great touch and overall I think the director used the deaf part to enhance the story, and not made it an excuse for the hero to fall. I also liked how they had their phones with them