Seeking for Death
A horror manga about school girls clinging onto the mc (while clinging onto their lives) and making him decide which of them he'll save. Similar vibe with "School Days". Shitty ending but AMAZING art style. Deaths are average. Needless to say, I always go for yanderes.
ARISA
Not exactly horror but it has many plot twists and kinda similar to "Ousama Game". Features less gore and more suspense. The art style is a MAJOR PLUS, I like how the mangaka used cute, shoujo drawings and turned them into one creepy, mystery story.
Franken Fran
Multiple stories, each with a plot twist at the end. MC is a hawt female version of Frankenstein. Very gory, imagine 'mad scientist performing gruesome experiments on her clients' only this time, the protagonist does so for the sake of 'helping others' and not for spreading terror in humanity.
Tokyo Red Hood
A very disturbing, twisted version of "Little Red Riding Hood". I dropped this early on but I plan on finishing it some other time. Not a big fan of the art. The gore is good tho, and the mc's messed up in the head so it ain't all bad. It's about a little girl's quest on finding "Mr. Wolf", whom she fantasizes on devouring her.
Murcielago
Exceptional in terms of gore. A bit explicit, has yuri 'scenes'. Not really scary? The MC is a psychopathic killer who agreed to work for the police and chase down criminals with her female partner/love interest.
Warehouse
RAPE, all chapters. Kinda repetitive but damn. Things had gotten so cruel for the mc, it's hard NOT to anticipate an update (which comes out VERY often, might I add.) Similar with KS, in the beginning only lol. Can't wait for the seme (or seke) to unleash his psychotic side :}
Ibitsu