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.

Yuuto is an ordinary run-of-the-mill high school student. But one day he gets struck by lightning, and things start to take a turn. A strange person, who goes by the name “Kazuchi”, shows up and starts following Yuuto around. Kazuchi turns out to be a ghost with mysterious spiritual powers, and proclaims (insists!) that Yuuto is the reincarnation of Princess Aki from a thousand years ago. Now, Kazuchi won’t leave Yuuto alone until he remembers who he really is!

From DMP

Even after all these years, you’re still the only one I think of… I’ll put all of my feelings into this letter for you.

A story of a one-track love, desperately wanting to reach its destination.

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.

Collection of oneshots from 1986 to 1996 by Sugimura Shinichi, including
*Prologue 1 (scanlated)
1. Snow Blind (scanlated)
*Prologue 2 (scanlated)
2. Carnaval 1999
*Prologue 3 (scanlated)
3. Kobayashi-kun (scanlated)
*Prologue 4 (scanlated)
4. OLDK chiku 25 sai
*Prologue 5 (scanlated)
5. BUN BUN BUN
*Prologue 6 (scanlated)
6. Taxi Driver
*Prologue 7 (scanlated)
7. Shoujo Camera (scanlated)
At the beginning of each chapter, there's a humorous prologue with nude-theme.

From Mangascreener:

The only common feature running through these stories is a grown-up protagonist somehow coming face-to-face with his childhood past, in a testament to the loss of youth, the disillusionment of growing old, and nostalgia for better times.

In the Adachi pantheon, this is a rare diametric view of his eternal theme of "youth," in this case youth as seen through the lens of the past. It's a powerful statement from Adachi that might even be an acknowledgment of his steadily-creeping age.

What is impressive about these stories is not the plots or characters themselves, but the absolutely perfect way he tells them, another facet of experience that comes with age. Most of the stories may require multiple readings to fully appreciate the airtightness of the plot and visual motifs."

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]

From Manga Art: Kojima has a crush on a boy, but doesn't dare tell him. When Kojima thought, "If only there were just the two of us left in this world, I could confess," the god Jinmen shows up and grants her wish by lending her the time trap clock! With this, she can freeze the world, leaving just her and her crush...

Toshiki is a below average student and often the target of ridicule. After he accidentally runs into a shop sign and breaks it, he enters the shop and finds out it will sell him abilities.. But these abilities don't come cheap.

Compilation of 6 stories with a realistic feeling to them:

Shiki no Zenjitsu
Two people spend the last day of their cohabitation together before she gets married.

Azusa Nigou de Saikai
A father visits his daughter when her mother isn't at home.

Monochrome no Kyoudai
Two twin brothers reunite for a drink after ten years.

Yume Miru Kakashi (1st part)
A man who left for the city ten years ago returns to his home town for his younger sister's wedding.

Yume Miru Kakashi (2nd part)
The returning brother reminisces about their childhood in the countryside.

Juugatsu no Hakoniwa
An unknown high-school girl moves in with a struggling writer.

Sorekara
A cat observes the actions of her mysterious and rude owner.

Fate/Zero takes place ten years before the events in Fate/Stay Night, detailing the Fourth Holy Grail War in Fuyuki City.

Soon after transferring to a new school, Mayu Kodabutsu recieves a love letter from a cute girl named Yuuko Hai... Expecting the envy of his classmates, Mayu is surprised to recieve condolences instead. You see, Yuuko Hai is no ordinary 5th grader... She's an exorcist. And Mayu is destined to experience her 100 terrifying ways.

Eru Yamada can't seem to get away from the supernatural. She's being stalked by a vampire. Her teacher is a werewolf, who also happens to think she belongs to him! As if that wasn't enough, yet another boy with supernatural powers shows up, trying to get her to fall for him, and she winds up with a rival in love who has dangerous powers as well!

From Storm in Heaven:

Judges are the messengers of the Central Government, sent out to punish delinquent cities. They have the ability to control programmed "seeds", causing explosive growth. After a disease breaks out among the "Children of Babel", those Judges who're given power through Central's research, Central requires the data of a natural Judge like Sion. However, Central is also interested in the legend of the "Heavenly City", which Sion is named after; what could their true purpose be?

From Within Silence:

Life isn't that great when it's composed of a stubborn sister, single mom, and a dad that left you for someone else? If that's not enough, you meet a dwarf that's part of a famous boy band? Could this get any worse?!

From StarryHeaven:
Ema is obsessed with ghosts, and is even part of her school’s occult club. She’ll do anything that has to do with some crazy superstition about ghosts or spirits, and make sure that she goes out of her way to do it. Ema is known for this at school, and the series follows her pursues to find ghosts. Ema, unfortunately, cannot see the things that she loves, unlike a few of her friends…

Included one-shots:
Volume 1: Shuugaku Ryoko no Susume
Volume 3: Time Capsule and Happy End no Tsukurikata

*Scanlators stopped because of lack of interest in chapters 2 and 3.

From MangaHelpers:

On his seventeenth birthday, Amamiya Kota was going to ask his classmate Misora Hiyori out. Tragically, he dies in a car accident but is given a second chance back in the living world on borrowed time. He gets entered into a competition called the 13 Game where other people like Kota who were supposed to die return back to the world and given an option: locate and kill 13 other players or suffer the fate of death. Each player is assigned to a handler, mysterious beings with special powers, who use them as if they were characters in a video game. Kota’s handler, Merume, explains that there are players like him all over the country, each with a unique ability that helps them kill, and Kota has to kill 13 players within 1 year. With his demon hands ability that was inspired from his hobby of magic tricks, Kota must unwillingly participate in this cruel game if he wants to live. [vyc]

From Heroines of Fantasia:
16-year-old Tsukimi Hina decides to get a part time job as a maid, and successfully passes her interview. One thing though: she can't use modern technology inside the house whatsoever?! Which means no vacuums, no cellphones, no laptops, etc. What is up with her twisted, but handsome, employer Asakura Shiyuusei-san? And what exactly is he hiding in his storage room...?

From Intercross:
16-year-old Hina's first job is with a 19th-century British enthusiast, Shuusei-san, as his maid. Even the way of cleaning has to be from the 19th century! Even so, this sweet gentleman makes Hina's heart beat so fast! There is actually another person in this residence, Mary Lou. She's as cute as a doll, but... she's, she's... a ghost?!

In this small town, within the 49 days after a person dies, you can see the dead's spirit. She once admired this small town where you can still spent time with the ones precious to you within these 49 days, but...

Includes two oneshots (not yet scanlated):
Soko ni Koi Ari (そこに恋あり)
Kimi wa Nanimo Hoshigarazu (君は何もほしがらず)