Amazing acting and the storyline was nice. Great buildup, I've notice the hint, of who's the killer but we shall wait for the buildup through the episodes,

DaeSung is an amazing man, with high IQ, however failed in his attempts to become a 9th grade public official within 3years. This is due to his psychology issue, due to past trauma.. However, he has a girlfriend that has been with him for 20 years. In this world, there's not many living person that has warm heart like DaeSung. Although he is the only child in his family, but his parents has brought him up with full care, and a very well environment. Allowing him to bloom with warm heart to other people as well. His nosiness and care for other people has lead him to help another person. As adult, he is able to listen to a small kids concern. And notice the difference.

Update: I've just complete the last episode today. In the last scene at the mart, we can see how desperate DaeSung mom is when he suddenly close the mart door, to confront the killer by himself.
It is really cheeky of the writers to end it with A Hee's father coming to the mart to buy pinneapple hahahahaa >.<)/// The music score is amazing!