First issue of a canceled series; collected (in thumbnails) in Blame and So on (Artbook)

After his mother's death, Kuro Takagi transfers to Yotsuji Private High School where his father is the proprietor. But Yotsuji is no ordinary school. It holds a strange rule of “No students on campus after dark!” On his first day of attendance, Kuro and his classmates inadvertently break the school’s highest protocol and find themselves victims of a faculty zombie attack. Although they manage to narrowly escape, this is but a prelude to more encounters with the undead, especially after Kuro discover his own blood-ties and latent zombie abilities. From there, it's full steam ahead as this dark and intense action/comedy shifts into high gear.

A manga about people trying to kill themselves, but weird stuff happens instead

Chris Redfield and Jill Valentine arrive in a remote Russian village to check on rumors that a wolf infected with the T-Virus had attacked its inhabitants. It wasn't long before the two ex-STARS officers found them battling against the villagers, now turned into zombies.

The human race has been infected by a strain of bacteria that was originally isolated in South America but has spread all over the world. The symptoms start with fever and vomit and eventually ends with the person in a coma. However, those who awake from that coma are those with incredible intelligence and they're soon able to see that they are in fact being ruled by higher beings that they thought only existed in fairy tales like demons and witches. Arthur Pyuty was a witch who ruled a kingdom under the guise of a human until the side effects of the bacteria revealed her true nature to humans and they started revolting. In fact, Arthur and her kind, who used to hold high political power in society, are now being hunted down. Arthur and her assistant Ataru, a zombie, must move from place to place in order to avoid humans but also so that they can find a way to make things go back to how it was before.

Yashiro Tenshuu killed 4 people, and is now on death row. However, a secret government organization is willing to take him off death row if he allows himself to become a test subject to an experiment that requires a killer's intent.

From Fantasyshrine: Since he first met Baron Kuroba, Seiji has been secretly in love with the master of the Kuroba Manor, where servants were rumored to be attacked by a vampire. However, Baron Kuroba only sees Seiji as a lap dog that needs to be disciplined for his carnal pleasures. How can Seiji convince the baron, who doesn’t believe in love, to love him back?

Infro from Manga Updates: Have you ever wondered what it would be like if manga panels were 3D rather than 2D? Kago Shintaro expresses this idea with the usual violence, sex, and oddities.

From MangaHelpers: Natural selection has created a deadly new species known as "Eclipse," who are driven to eliminate humanity. A scientist called Kurusu Kenji headed an organization whose purpose was to fight these deadly creatures of bone. To this end, he created the "Osteon," Eclipse-like creatures that obey the commands of the human from whose DNA they are created. Now Kenji is gone, and his assistant Kidogawa Rokuko is attempting to recruit his estranged teenage son. Kurusu Akira wanted nothing to do with the father that he believed abandoned him, but attacks from Eclipse force him to accept his own Osteon from Rokuko. He slowly finds himself drawn into the organization, whose members expect him to take his father's place. Akira and his Osteon may have little interest in protecting humanity, but they are determined not to be beaten! [tethysdust]

Vampires exist. It is the duty of Hellsing, an organization sponsored by the British government, to hide that frightening fact and protect the blissfully unaware populace. Along with its own personal army, Hellsing also has a few secret weapons. Alucard, an incredibly powerful vampire, has been controlled by Hellsing for years. Although he dislikes being a servant to the Hellsing family, he certainly enjoys his job as Hellsing’s vampire exterminator. Seras is a fledgling vampire and a former police woman. Although reluctant to embrace her new self, she is still a valuable member of the organization. Integra Hellsing, the current leader, is usually fully capable of fulfilling her duty, but lately, vampire activity has been on the rise. Unfortunately, the cause is more alarming than anything she could have imagined. A group long thought dead has been plotting in secret since their apparent destruction over 50 years ago. Plotting to plunge England, and perhaps the entire world, into war.

If you wished for your own death, how would you like to go? Here is one boy's encounter with a grim reaper...

On the secluded island of Rokkenjima, Battler Ushiromiya and his family were trapped and murdered under unusual circumstances attributed to Beatrice, the Golden Witch. After continually challenging the existence of magic and powerful witches, Battler has become the Game Master of the board involving the mysterious events that occured. To prove his understanding of the mystery, he must defeat Erika Furudo, the detective and piece for the witch Bernkastel. Meanwhile, a childlike Beatrice, reborn through Battler's efforts, struggles to regain her former personality for Battler's sake. As the new game begins, the unfolding events are brought into existence by two objective observers: the Witch of the Theatre, Featherine Augustus Aurora, and her chosen reader, Ange Ushiromiya, Battler's sister as she is in 1998. On Rokkenjima in 1986, love becomes important to understanding the truth behind the events, particularly as it pertains to George and Jessica Ushiromiya, and the servants Shannon and Kanon.

A oneshot that appeared in Comic Flapper 2015-02.

Ever since she lost her parents in a fire two years ago, Natsuki has been seeing horrible nightmares, where an unknown boy pierced by tree roots calls out to someone named "Dakini"... Meanwhile, students around her start dying... What has Natsuki forgotten?! A three-volume dark horror mystery! From Manga Reborn

Aoi and Haru and secretly dating. However, Aoi notices that Haru has been worried about something, and the next day, he sees her fall from the roof of the school. He then discovers that she put a chart of relationships into his locker, and marked five of them as "clowns" who are trying to kill her.

Nothing can be explained, strive to the unknown. Lostworks is an isekai thriller with a heavy focus on action and mystery. If you want a more mature story, one that escapes the saturation of the genre and that deals with philosophical questions and dark topics, I believe you should give it a try.

Mysterious alien life-forms invade Earth! Most of humanity is wiped off the face of the planet. John, his sister, and the remaining survivors hope to find a new world to inhabit… But one day, they’re targeted by aliens again!

After her failed sc1c1d3 attempt and finally set free from a mental institution Radka, a 20 year old ex. college student, has to move back to her childhood home into a small town in Transylvania. She decides to pursue studies in film and whilst looking for inspiration she realizes that her old hometown has some secrets that have escaped her attention before

A series of short horror stories featuring various characters from Mob Psycho 100.

In the city of Brudill, shapeshifting entities known as the Gunk invade causing destruction and misfortune to the citizens. To counter the Gunk, the Gunk Annihilation Service or GAS was formed. GAS now vows to protect Brudill by using the Gunk against itself with their Agent, Miles Mercer fusing with one codenamed, En to become GAS's ultimate weapon, "The Ripper".

Updating

Spook is a supernatural Horror/Romance Follows Charlie balancing her life with the living as well as the realm beyond the veil she is left with. joined with her is the dapper shade Griffin and faced with a tod who hides his own demonic secrets

Tateyuki Chono is devastated when his apartment and extensive collection of insect specimens burns to the ground one evening. But his luck turns around when a chance leads him to meet famed entomologist Izumo Kusanagi. Chono is floored by the kind hospitality of Kusanagi and his beautiful daughter Toko. However, the warm atmosphere of the estate belies a sinister secret. What is the true nature of Dr. Kusanagi’s research? And is Chono already trapped in a deadly web of terror?

Arch Extent has spent years finding a cure for Cosmos Plague with very little results. Earth is on its last leg before hitting extinction. That is...until he meets a huntress on Division 5. Meet Winter: the potential cure for Cosmos Plague. What do you think happens when a scientist meets a huntress who is immune to Cosmos Plague?