Cruel Intentions (dark manga)

The true horror of a bloodthirsty individual that lacks morality. Drawing style may turn readers off but it truly adds to the experience. It doesn't want to be pretty, it wants to be terrifying.

gore, rape, death, murder, sexual contact with minors (not sexualized)

Psychological damage and trauma inflicted on the protagonist actually makes you pity him. The characters are intriguing, and the gore featured isn't overdone but remains unsettling.

gore, rape, kidnapping, murder, drug abuse, manipulation, obsession

The horrors of the human mind are incapable of surpassing supernatural entities that showcase their power, so what can one do but embrace the darkness. An interesting story of losing humanity and power struggles

gore, manipulation
climbing up a power hierarchy

a necrophilic narcissist prince who has a fetish for big breasted women sets off on a journey through a fairy-tale land to seek a bride after his father (the king) demands him to.

necrophilia (referenced), death
abnormal sexual interests

the overarching story is about a man who is sexually harassed at work that finds a strange and unfamiliar pet shop owned by an unusual man. Within each chapter is a background story of mysterious 'pets' being given to people.

stockholm syndrome, manipulation, psychological torture, rape
desperation, obsession

No list of twisted manga works is complete without Harada. I didn't want to place all their works on here but I recommend reading them. One of the first manga I read from them, which lead me down the rabbit hole of cruel manga. Don't need to be a gintama fan to read

The feeling of alienation from others due to immoral interests brings two adolescent boys together.

abnormal sexual interests, loneliness, alienation

The backstory of one character from Saezuru tori wa habatakanai: http://www.mangago.me/read-manga/saezuru_tori_wa_habatakanai/

a stalker whose obsession with a man turns out to be based on false assumptions.

confinement, manipulation, torture, abuse, rape, death, murder
obsession

(another mandatory story for a list such as this. pretty sure everyone knows about this one lmfao.)

two blood related friends since infancy are trapped in a unbalanced power dynamic as one seeks control whilst the other is willing to do what it takes for them to stay together

incest (cousins)
desperation, (vague) slave and master dialectic dynamic

Mikaya's new residence only just belonged to another person a few days before. Despite never being found, his strange neighbors in the apartment building seems to know that man, K, is dead. Curious to find the body, mikaya begins to learn about K's true character and uncover which of his neighbors may have killed him.

death, drugs
loneliness, alienation, uncovering a dark past

a gorgeous gothic story with eccentric characters and even odder situations. one of my favorite