Based on the erotic manga by Akazawa Red.

What are some of the most disturbing manga and anime of all time?

Oh this question is for me.
Here is my list:- Ichi The Killer A tale about two people.
One is the ultimate sadist and a contract killer, the other being the ultimate masochist and a yakuza general.
This is their story of blood, gore, guts and well some semen It’s made by one of my favorite artist Yamamoto Hideo Homunculus Another one by Hideo San which is disturbingly beautiful.
In this, the protagonist undergoes a procedure called trepanning(basically drilling a hole in your skull) after which, he gets to see caricatures of people for who they actually are. Ibitsu by Harrods Ryo How would you like a younger ghoulish sister? She is the reason why I stay away from garbage dumps at night and why I draw the curtains in front of my windows.
I'd rather die first than become her big brother and then die later. Well done Ryo sensei.
You have managed to make a grown man piss his pants. Rainbow: Nisha Rokubō no Shichinin Set in the 1950’s, it is a story about six delinquents and their life in a juvenile detention center.
The reason this one is disturbing and tragic is because….
Well let's just say life does not treat them very well.
Made by George Abe. Right now these are the only ones I can think of.
I might add some more later.