Somewhere in Tokyo, there is a room. In that room is a black sphere. Periodically, people who should otherwise have died are transferred to the room. There, the sphere gives them special suits and weapons and sends them out on a mission to kill aliens here on Earth. While these missions take place, the rest of the world is largely oblivious to them. These missions are lethal and few participants survive them. The sphere calls the shots and it's not the slightest bit nice. Its name: Gantz.

It's the year 1994. As a young otaku from the countryside, Nakai Junpei has learned to keep his hobby a secret. His only fun was drawing erotic manga about his classmates. After graduating from high school, he was accepted to a college in Tokyo, where the bookstores are abundant. While there, he also finds the one thing he was hoping for most - a manga circle.

Kurita Yomi suffers from an unfortunate affliction -- when she sleeps her body can be possessed by others. She benefits in her own way from these experiences though...

From Casanova:

After being kidnapped by an "alien woman", Yuuta developed a severe case of gynophobia. Having to be in charge of a bath house, Yuuta couldn't be more inconvienced by this. Just when he was thinking of trying to cure his phobia no matter what, a beautiful girl called Uni suddenly appears in front of him, and that's not all, that girl says she's the daughter of the alien woman who kidnapped and that her mother won an award by investigating him. Her mother feels truly grateful for this so she sent Uni to repay Yuuta with anything he desires and told her not to come back before she does it. What will happen after Yuuta asks her to cure his phobia in the least painful way possible?

Mukai Sachi is extremely unlucky. Stubbed toes, lost items, bird poop... it all happens to her. Her most unfortunate problem, though, is Gokurakuin Misako, the only member of the Occult Research Society. Misako is an honors student, beautiful, very strange, and friendless. She is interested in Sachi's "power" because she wants strange, unexplainable things to happen to herself, too. The problem is that Sachi has absolutely no interest in the occult, so Misako's continued, oddball attempts to get her to join the Occult Research Society are yet another piece of bad luck for Sachi!

In a not too distant future, the world is confronted with a host of issues: pollution, resource depletion, population expansion, and so on. In response, the Japanese government developed sensory simulation capsules (“beds”) and successfully launched a virtual reality program — “Gaia.” Interestingly, the designers omitted the concept of pain from the program, and as a result, there are no such things as pain or death in this new virtual world.

On a day that started as any other, Oono Yuuri stumbles across a mysterious card, which sets off a chain of strange events that evolve into a tale of conflicting dreams, unlikely friendships, and reluctant vengeance.

From MangaHelpers:
A terrorist group has declared independence on the South Pole, and they have placed extremely powerful nitrogen bombs off many coasts. They plan to take revenge on the world, by forcing them to live briefly in fear and then die. The US tragically failed to defuse the bombs. There are three of them off the coast of Japan, set to explode in 10 days. Luckily, the Japanese bomb disposal team has a powerful resource.
That resource is a little genius girl, Machida Machiko. She's looked after by Aranagi Nagito, a trainee bomb defuser. She's made a pact with him, and with the leader of the bomb disposal program, to clear out the bombs and clean up the world. After certain events in their first defusing operation, though, it looks like all they'll have left to use is a defusing program written by Machiko. Will they be able to save Japan and stop the powerful terrorists?

A collection of several absolutely intense and violent stories. They are gorey and crazy. The first is about a woman who has mantis-like arms and uses them to sever heads, and then in turn uses those heads for her own special purposes... Read to find out. The same main character is used throughout. If you love murderous koala bears, read!

Cutie Honey for the 21st Century.
Seiko Hayami a private detective and her partner Hisashi Hanyu, are tasked with solving the cases that the police can’t handle. What they soon uncover is a seedy underbelly of crime perpetrated by an organization that can turn humans into monsters.
With Seiko being overwhelmed by these outrageous cases will a hero arise to help in her stead?
A warrior of love only heard from stories long ago.

Tadanori Takamura is a failure in everything he does. His job, his marriage, his life. One day, he is offered a way out of his hell (by a 3-fingered woman): A gambling game called "cowarDICE". Shady characters and dark moods abound in this intense gambling drama by Noboru Takahashi.

(Warning: contains sex and adult content)

Spinoza has been printed in 7 issues of Photo Japon, from december 1985 to june 1986.

Each issue contains a whole chapter, printed on one page. The format is that of a contact sheet, with the pages shrunk to fit on a single page.

Manipulating a demon with a worm-eaten body, the girl exterminates all sinners!! Accepting requests from the families of victims killed unreasonably, boys and girls are set on continuing to kill the sinners. They are responsible for this business without knowing when it will end, but also unable to live a different life, today also they open the curtain of revenge

An audiophile jumps to his death, meets something on the way down... and ends up crawling away from a pool of his own blood.
An unmotivated music high school student (our main protagonist) vs. a speeding truck meets the same fate in front of his friends.
Now those two must kill each other "in order to understand the joy of living", as proxy, with the power of classical music incarnated.

From AnimeWaves:
Touko's life seemed so ordinary, until she got that call... At the scene of the accident, by the puddle of blood, a young maid appeared... could no one else see her? And then, around the corner, a cry for help from a silver-haired boy... The veils are being lifted and the truth is being revealed!

From Japanzai:

In the edges of this world, demons known as "Pagans" lurk. Pagans are born when the souls of the recently deceased fall off the path to reincarnation. The reincarnation ceremony must be performed under moonlight, and so cannot be performed inside a city like Faith-Dehli, overly shrouded by both constant mist and thick smoke.

The Twanbach Funeral Service Company specializes in hunting these Pagans, especially those that attack while Twanbach delivers recently deceased bodies to the reincarnation ceremony—because there's nothing Pagans desire more than freshly dead human bodies with the souls still slightly attached.

Reginald, a 100+-year-old vampire who looks like he's 20, gets scouted by the Twanbach Company owner's mysterious twin daughters, Vanessa and Veroinica Twanbach. But first, they'll hunt Reginald a little, to see how far off the path he's fallen...

From MangaHelpers:
One day, Son happened across a woman, named Shue, that he had loved as an older sister when they were young. It looked like it was the same woman, with the same scars, but Son had thought she was dead. In fact, she was a reanimated corpse, resurrected by a young girl named Fuu to work as her minion. Son becomes Fuu's follower, determined to find a way to return Shue's soul to her body so that she might live again. However, Son doesn't know what he's gotten into with Fuu, though, as she ends up in conflict with many other practitioners of her arts, using Shue's reanimated corpse to do things that Son would rather have never seen.

From MangaHelpers:

"The Sixth Dimension Experiment." This experiment, in attempting to open one of the eleven dimensions in our reality, the sixth dimension (Secht), resulted in a catastrophic explosion that killed 110 million people and left 12 countries in ruins. The originator of this experiment, Himeka Yuki, bearing the total responsibility for the failure of this experiment, has been banished from reality for eternity. In response to this event, the world leaders in sciences formed a monitoring agency known as "Zeien" to keep control of all scientists and technology in order to prevent another Sixth Dimension Experiment.

10 years have passed since the incident. Takaomi Yuki, the younger brother of Himeka, notices a change in the "Time Machine Destination" that his sister has given him before her banishment. Suddenly, the device summons a lively girl armored with metals he has never seen. "Takaomi-san! To save Earth, pull out your lance and ride me!" To uncover the truth, the two will begin an adventure that crosses time and space. [DrCoke]

From Animeraider:
When 16 year-old Haruna runs away from an arranged marriage, her parents force her younger twin sister Wakaba into the marriage instead. But while Haruna ran off with a boyfriend, Wakaba has never even been kissed. How will a high school girl survive going from nothing to full on marriage with no steps in between?

This is oneshot of Tokyo Ghoul.

The manga consists of nine entirely separate short stories set in World War II, each reimagining a famous fairy tale with the European theater of World War II as a backdrop, often with poignant results.

(Source: Hokuto no Gun)