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)

3, Street of Mysteries explores the fantastical-poetic vein that has forged Mizuki's reputation in Japan. The stories contained in this series hold in common the obsessive ideas of immortality and of life after death. Skillfully blending a range of black humor, drama, and questions of morality, Mizuki shows once more his profound understanding of the human soul.

(paraphrased from Astiberri)

After she died from an accident, Ria become angel No. 5623. She could not forget her life from when she lived. She misses Ban Ji Hwan, her boyfriend on Earth, day and night.
1 year later, Ria happened to see Ji Hwan's name on the death list, the list of every names who is about to die in 100 days. Ria begged high-ranked angels to let her save Ji Hwan. Ria entered the body of So Hae, a shy girl who is tired of her life, the opposite of Ria's personality. Enduring the bullies from step-siblings of So Hae, Ria did her best to bear everything in order to look for Ji Hwan. But when she found him, Ji Hwan cannot recognize Ria...

An art college students moves in Venice to study, she starts to live in her new room, part of an old huge historical mansion and she discovers a new world of secrets linked to her young, mysterious landlord. A gothic romance story and a vampire tale which flows around Venetian laguna and roman museums; a manga rich of suggestions and images with a passional storytelling, a deep noir drawing style and melancholic mood. From Italians to Japanese. This was created for Kodansha, published on Amie. You read it Japanese style.

• The Power Plant
• Vacation of the Power Plant
• The Great Traffic War of the Power Plant

• Hidarigawa ni Ki o Tsukero (Guard Your Left)

• Aru Eiyuu no Shi (A Certain Hero's Death)
Imagine, that the roles of whales and humans were swapped. So whales (or whale-like creatures) would be rather small, able to talk and smart. Humans would be large, stupid and hunted by whale-people.

From Manga Updates An ordinary high school girl, Lin Seonu, unknown even to herself is actually a woman saint holding ancient power called the "Jade of Bango." On her seventeenth birthday, she obtained the power to see ghosts, and every morning after that she goes to school accompanied by the harmless and lovely ghosts. One day, however, Lin has an abnormal dream, and that evening, she encounters a terrible evil spirit. Shivering in horror, she is rescued in the nick of time by a handsome man she had seen in a dream. He frees the ridiculous power that had been concealed in her. He says that his name is In Mu, and that he is her fiance.

7 Short Stories About Sex (spanning across 11 chapters):

1-3. 7 Daime no Tomari (The Seventh Generation, Tomari)
Tomari is a cursed woman who must do specific sexual things with her partner or the curse will kill her. Her partner, randomly chosen by the curse, is a guy called Naoki. He's pretty much willing to do whatever she needs, but Tomari will have to get past his incestuous sister Kyoko first.

4-6. Hajimete to,
A teenage couple, Seriko and her boyfriend Ogihiko, find themselves caught in a plot from her crazy yakuza family to make them lose their virginity together.

7. Sandy Go Home
Yoko returns from studying abroad in America with her sex-crazed roommate Sandy, and they both proceed to fight over who gets to have sex with her brother.

8. Mete Yunde
After their parents died in a traffic accident, Morote's two older sisters became insane. Is he safe in the house with them any longer?

9. Pastel Ivory
School kids have a sexual encounter in a bathroom.

10. Ninjia Shoujo Makari Tooru
When a ninja invades a girl's bedroom, he finds himself completely outmatched by her skills, both ninja and erotic.

11. 80D
A couple has a sexual exploit in a library after hours.

From Shoujo Crusade:

One day, while in search for more food, our heroine stumbles upon a jar of what looked like umeboshi; little did she know that it would bring her more than just a full stomach. The mysterious snack somehow makes her shrink and she can only grow back when she eats something (which is a bit of a chore if you're THAT tiny). And if that's not troublesome enough, she's also dealing with her crush who seems to like her best friend!?

After a tragic accident at a large facility 6000 meters below water killed its workers, the facility was abandoned for three years. After the Japanese company owning it is taken over by a Chinese company, the facility will be opened again. Kadokura Kengo and his colleague Danzaki are sent along with the team reopening the underwater facility. However, right away, an 'accident' grievously injures Danzaki. Kengo is left alone with colleagues he doesn't trust in an eerie underwater environment that may have more to it than meets the eye...

Haizuka just wants to live a normal life, a peaceful life far away from all the trouble he's faced. But as soon as he starts highschool, an encounter with a girl and a strange creature destroys any hope of a peaceful life.

Reika Ryuzaki, daughter of the late diamond collector Yoshio Ryuzaki, is a jewel specialist who fights with knuckles branded as "Krishna" in cases involving bad guys who rob or misuse jewels for their own gains. She has an advantage in fighting as she can summon spirits from certain jewels to aid Reika in making her a better combatant in the field.

"I am, in fact, one of the dead."

So says Acony, a rather mischievous girl, upon her first meeting with protagonist Motomi. Newly moved into an ancient apartment, how will Motomi handle Acony and all the bizarre residents?

From Iskultrip Scans:

Japan wields the power of a new form of influenza so lethal that only one person out of a million can survive an infection. Kazuma, a man able to withstand the infection of the unknown virus, "Cherubim [kerubimu]," has obtained the power to save his twin sister from facing the influenza! While Kazuma saves other people's suffering by using his new power, he will also encounter many surprising and painful things… A serious and comedic story of new abilities begins!!