From Entropy:

In the languid hours of yesterday, I went to the tangled grasses near the river, so tangled that humans don’t often venture there, and had heaps of fun playing alone. As per usual, I had had a glass of sue-ju with grandmother in the morning, and drunk, I grabbed a towel and stumbled my way up. There won’t be any watchers, my body thought, and it slipped so easily into the water. Floating in the clear and pretty water I looked at the sky, saw the floating clouds. Hee hee… in that small space I even had a go at swimming like the pros. If you sit on the rock and rest for a bit you can see the small sand-colored fishes swimming around. Even such small creatures made shadows on the river bed and moved around. Yeah, every day I play at being a mountain wizard. Whether the axe handles decay or not… violets.

It happened after school one rainy day... A group of friends have stayed behind to prepare for the next day’s school festival. One moment they are idly telling ghost stories but the next an enormous earthquake strikes and the entire school seems to fall down around them. They awake to find themselves trapped in a parallel version of their school. A school abandoned and disheveled and whose calendar dates back to 1927. Can they find a way out of this nightmare or are they doomed to the same fate that befell the other victims whose corpses that lie numerous throughout the school?

From Kotonoha:

Seventh grader Hayashi Renei is troubled by a strange dream: Her dead brother, who was killed in an automobile accident, comes back to life as Coo. The dream comes again the following night and then every night thereafter.

Coo's world is a cruel one--crueler than the real world, even--with its own share of pain, suffering, and sadness. Renei is searching for her house with her brother and others whom she meets in Coo's world so that she can return to reality and the land of the living...

Taking place approximately 50 years after the original D.C. - Da Capo series, the story revolves around Sakurai Yoshiyuki and Otome & Yume, the two granddaughters of the original D.C. - Da Capo protagonists Junichi and Nemu.

This is actually the second manga based on Da Capo II in active serialization. The other manga, running in Kadokawa’s Comptiq magazine, is considered to be the “canon” adaptation of the story (i.e. it’s based directly on the game). As the title “Imaginary Future” suggests, this manga proposes an alternate deviation from the game’s premise, where fan-favourite Shirakawa Nanaka (speculated to be a descendant of the famous Shirakawa Kotori) is the story’s main heroine.

From Anime Waves:
Tsukasa, Tajima, Katsu, and newcomer Sae, were all members of the Hentai ShonenDai (Perverted Boy's club) at the tender age of 11. But as they grow older, how will each of their lives change? Will they grow apart, or stay true to the (perverted) passions they shared as kids. D-ASH is a story about the adventures these boys will have trying to grow up as fast as they can, being as naughty as possible all the while.

Kasuga Rito had a hidden wish for a very long time: to use his ability for good and to help people. But before he could do that, he needed to gain the power of magic first.

Rito is a sophomore in Rezon Institute, a school for people with special magic abilities to find, train, and develop their skills. Each student has to reach 100 points to be able to start using their ability. Otherwise they won't move up from the "Common" and into the "Starlight" class. But Rito, known as "the Eternal 99", has been stuck with an unchanging 99 points for a long time.

So here comes his new plan: to become a friend with Scuse Fontana, a three-day exchange student from the Demon World, and to ask her for some food. (There's rumor that a human can increase his power by eating food from the Demon World). He slipped into the hotel where a welcome party is being held for the much respected lady, just to find that she's actually absent. Losing hope, he wastes no time leaving the hotel. At the back alley behind the hotel, he finds a tiny dragon, which for some reason sticks to his head and now he can't get it off...

Asano Inio's first official art-book. Contains two short stories: "Wish for spring" (はるよこい~solanin side story~) and "The sunflower" (ひまわり).

What lies below Tokyo's subway system is more frightening than you could have ever imagined...in its subways there exists a boundary between this world and the next--the land of the dead, and the mysterious young man Seiya is its guide. In this collection of bone-chilling shorts, follow the twisted tales of death and hauntings that inhabit this horrifying underworld, where innocent youth fall victim to the ghosts who inhabit Tokyo's underground.

Note - this was originally a GlobalManga, and not of Japanese origin. However, all 3 volumes have since been issued in Japan.

From Easy Going Scans:

Once... Humans and Orcs peacefully co-existed, but at some point humans got greedy and started a war claiming the Orcs' territory. The diety-Lord who created all, got angry with the humans' greed and decided to punish them with 3 catastrophes. One of them was the "Dragons", divine creatures blessed with magic capable of doing almost anything. Now the Orcs, with a "Dragon" by their side, seem to have the upper hand. Will humans just sit back and see their land get destroyed? They are too devious for that... Their only good plan at that point is to abduct a "Dragon" to even things up. But how are they going to manage the capture of a being with so much power?

Note:Manhwa adaption roughly covers 2 volumes of the original novel Dark Mage (Novel).

Manga adaptation of Dante Alighieri's classic work "The Divine Comedy".

A small five-year-old girl named Subaru no longer has time for friends and play. Why is this? Her twin brother Kazuma is dying and gradually forgetting everything. Even Subaru. And so the girl visits him every day, talking with him and dancing for him, trying to make him remember her. And he always does by the end of the day. Encouraged by a friend to join ballet classes, the girl does so and falls in love with the dance.

From Illuminati-Manga:

At the turn of the previous century, the earth quaked. The earth's crust began to shift for the fourth time, centering around the coast of the Atlantic Ocean. The entire world's land mass was reduced to 3/5 of the planet, and the human population was reduced by a third. Put simply...the earth had gotten old. In 2039, there was only one country that continued to prosper, glaring around at the rest of the dying planet: Japan.

Todoroki Jin returns to Tokyo, the city where he was born, in hopes of finding his friend Ryoma. Little does Jin know about how Tokyo's changed since his last visit...

The oneshot at the end of volume 3 is called Warrior of the Holy Flame, Abi.

Recommended for fans of Riki-Oh

From Tokyopop: Shirou's ordinary life as a poor construction worker gets turned upside down when he comes across a naked girl, Lucy, who's fallen out of the sky! Her strange and unique personality entices him and he introduces her to his apartment buddies. But after leaving for just a few minutes, he returns to the apartment to find Lucy gone, all his friends slaughtered and an ogre-like stranger standing amidst the carnage. The big man suddenly pulls Shirou out of the apartment building just before it explodes! Shirou gets pushed down into the sewage system of the city and is saved by a mysterious man...

Comedy about a high school manga club. A frog god who can turn into a good looking guy lives in the club meeting room, but that has very little to do with the plot. He's there to just read manga.

At a glance, Oriko Amano is a cool, handsome male university student, whilst on the other hand, Natsuo Koike is small and childlike in appearance. However, the truth is that Oriko is actually a girl, and they are both twenty years old! Dekoboko Girlish follows the daily lives of Oriko, Natsuo and the other members of their university's classical theatre group.

Fudou Jun is a highschool teacher and takes a trip with a group of students. While there, a group of martial artists staying nearby take a strange interest in the girls.
These men are actually demons and after changing into their true form break into the cabin to rape the girls. One gets Jun and violates her.
She feels her soul being torn apart and transforms into Devilman Lady. With newfound powers and strength she kills all the demons and protects the girls from any further harm.
What are these demons and why did she turn into a hybrid of one? What does this mean for her and for the rest of humanity?

Gambling. Mahjong. Death. These are the themes of this fast-paced, undercover-agent-style manga where outrageous life-or-death gambles are made daily occurences and insurmountable odds are overcome. The most hardcore, action-packed mahjong manga you will ever see.

Included in the manga is a oneshot called Nana-chan Scrambles.

DeroDero is the story of a juvenile delinquent, Hino Mimio, who happens to also be a psychic. His ability to communicate with the spiritual world as well as his demeanors caused him to constantly interact with supernatural beings -- usually ending up with Mimio beating the crap out of the monster or spirit.

*manga is based on a true story and the true story was done in 2ch*

It's about an Otaku guy who fell in love with this beautiful lady and tries his best to get that girl with a lot of help from 2channelers (people who goes/posts on 2ch).

This story has become very famous in Japan and I believe they now have novels, several series of Manga (both Shoujo and Shounen), movie, drama, play, etc, etc.

A collection of short, bittersweet love stories, including several incestuous ones:

1) Until the Ice Melts and Turns to Blood.
The Karaoke staff call her "the lonely girl." She rents a room all night and won't go home. Why? And what can Nogami say to help her?

2) Suicide Note.
Two charming girls, Michi and Rina, decide to end their lives this day. As the day ends we slowly discover why: both the horror--and the hope.

3) White.
It happened once, years ago... Now it's all Minako can think about. She yearns to do it again. But how does her brother feel...?

4) Yellow.
She just wants her brother to look at her--really look at her as a girl, not just a sister.

5) Blue.
They were finally reunited after their parents divorced. She can't resist her feelings for him anymore. But will she lose everything for one night of bliss?

6) Prohibition.
A walk together. A stolen kiss. Tears.

7) Moon River.
A young man studies and studies while being afraid of his own problems of failing. Until he meets a girl with a specific problem of her own by the river...

8) Bitter Cakes.
Miho meets with her friend Natsuki, who is blind. Natsuki trusts her other senses--and herself. But Miho trusts no one--yet perhaps trusts her eyes a little too much...

9) Love Horizon.
A girl sees her high school crush by chance, but something is very different about him.

10) The Day It Rained.
A short political piece regarding a young man, and a doll.

11) No Count.
A young girl finds out that her first kiss was with her oniichan.