-> The story a.k.a the strongest point of this serie from my opinion.

The story evolves around "poverty", "psychology", "money", "teenagers/minors", "trafficking, sextrafficking, gangs".
At first, it sounds old and common but, the way the story is told makes this drama unique in its genre. The story telling of this drama is a work of art. I am not exagerrating, it is brilliant. The episode 1 is echoing the last episode (ep 10). The first episode set the atmostphere since the first scene and that scene is directly connected to the last scene of the last episode which resumes everything. The introduction is also the conclusion. It is very brilliant. Also the sentences that the professor told him are all so important to understand the psychology of the main characters especially Jinsoo. For example in the first episode, he told him if he endure everything now he will face the consequences all at once at the end. The professor is such an important character. Also there are many details which are very important as well, they seems like "nothing" but they are crucial like the animal that Jinsoo take care of and the cap Minhee has brought.
I truly appreciate how unique this drama is, how uncommon it is, how unpredictable and predictable it is at the same time, how it makes sense but doesn't makes sense at the same as well.

The four main characters were to blame, they were not saint and not evil either, they have taken the wrong path to achieve their goals and the consequences were tragic (Even MrLee is to blame). The two main characters especially are to blame, they are anti heroes. The story tellins is great because the way it is told will makes you want to support them even if they are wrong.

In addition, I also like a lot the fact that they truly portrays two kind of trafficking : the "old" kind of making money through illegal trafficking and the "modern" way to make money through illegal trafficking with modern technologies (smartphones, by distance). With mordern techologies, a lot more people with different backgrounds can dive into this illegal world "more easily".

If you like the movie "Parasite" you will love this drama. "Extracurricular" truly follows the same "concept", the same unique, new genre. I was really not into "Parasite" but with "Extracurricular" it is different. So if you haven't enjoyed "Parasite", this drama "Extracurriclar" can reconcile you with the concept.

-> The cast
The cast is very good, the acting very great. I'll not say I was complety amazed by their acting to be very honest but they are very good especially the main actor who is portraying Jinsoo.

-> The music a.k.a the only weak point
From my opinion, my personal tastes, the choice of the osts were not always good but that's my personal tastes who is speaking because I am aware the choice of some songs for some scenes were intentional to makes this drama "unique". But imo it is was unecessary "unique". The osts are good to listen, but they doesn't fit with this drama particularly. I only like a lot the "opening theme", it was the only ost that fit the drama. The others musics doesn't fit.

-> The rewatch value
I found myself wanting to rewatch again this drama because the story telling once again is brilliant.