Alive, the Final Evolution
Alive (oneshot)
MPD Psycho
Suicide Island
Jisatsu Circle
Franken Fran
Nononono
Banana Bread no Pudding
Godchild
Ludwig Kakumei
Ranma 1/2
Luck Stealer
Usotsuki Lily
Doubt
I have more and you did not specify on genre so some of these are mature rated. Alive, MPD Psycho, Jisatsu Circle, Franken Fran, and maybe Suicide Island are disturbing. MPD Psycho is high rating for mature content, sexual themes and gore. Nononono and Usotsuki Lily deal with gender benders, Godchild and Ludwig Kakumei is done by Kaori Yuki who has amazing talent. Banana Bread no Pudding will be weird, but good in a sense. It differs for most. Ranma 1/2 is a classic and the best ever. Doubt is good, but pyschological; it can be most likely put into a disturbing genre like the first ones. Luck Stealer I recently discovered and it's so good.
If you need more just ask.
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So why care for these petty obsessions? Your designer heart still beats with common blood.
~Grave Robber, Repo! Genetic Opera.