High school series that show the ugly side of society. it can be a kdrama or a jdrama.

something like Extracurricular or Class of lies 

I don't have any suggestions for you that are K or J drama unfortunately but I do have:

Thailand > Hormones (Three seasons, follows high school students. Not super dark like Extracurricular but follows a lot of issues and it's one of my faves it's really really good)

Taiwanese > Age Of Rebellion (Soooo good oml. Definitely darker themed.)

Thailand > The Gifted (Shows the uglier side of society through high schoolers + special abilities)

Thailand > Girl from Nowhere (Extremely dark and I mean extremely. *Tigger warnings for rape* Not for the faint of heart. It's excellent and perfectly shows the very dark side of society through high school)

All of these except the gifted are on netflix, the Gifted can be easily found on You Tube.

I seriously recommend these.

Angry Mom - This one is actually darker than it appears to be. It's a K-drama.

OMG I FORGOT ONE

I would also reccomend:

Thailand > A gift to the people you hate (This one is on you tube, it's another dark plot high school drama that's pretty good)

  • 3 Nen A Gumi: Ima kara Mina-san wa, Hitojichi Desu - hughly recommend this drama!!!
  • White christmas
  • Bad Genuis (Thailand)
  • Solomon's Perjury (JPN/KOR)
  • How to Buy a friend
  • Tong: memories
  • Kingyo Club
  • Re: Mind
  • Q series: have you ever fallen in love miss Jiang (TWN)
  • Jungle Fish 1 & 2
  • Everything and Nothing
  • Kuzu no honkai
  • Beautiful world