Gattsu, known as the Black Swordsman, seeks sanctuary from the demonic forces that persue himself and his woman, and also vengeance against the man who branded him as an unholy sacrifice. Aided only by his titanic strength, skill and sword, Gattsu must struggle against his bleak destiny, all the while fighting with a rage that might strip him of his humanity. Berserk is a dark and brooding story of outrageous swordplay and ominous fate, in the theme of Shakespeare's MacBeth.

Gantz tells the story of a teenager named Kei Kurono who dies in a train accident and becomes part of a semi-posthumous "game" in which he and several other recently deceased people are forced to hunt down and kill aliens. The missions in which they embark upon are often dangerous. Many die--again--on each mission, but they are replaced by others in the same manner as Kei Kurono's appearance. [from en.wikipedia.com]

Bookish and naive, Angelo da Canossa is unprepared for life as a student in a university that hums with tension and intrigue in Renaissance Italy. Will his innocence remain intact when a chance encounter with the charismatic Cesare draws him ever deeper into the darker side of the Renaissance?

Shinmen Takezo is destined to become the legendary sword-saint, Miyamoto Musashi--perhaps the most renowned samurai of all time. For now, Takezo is a cold-hearted kiler, who will take on anyone in mortal combat to make a name for himself. This is the journey of a wild young brute who strives to reach enlightenment by way of the sword--fighting on the edge of death.

Alone in his dorm room one Saturday night (a frequent occurrence, to be honest), young Keiichi Morisato accidentally dials a wrong number that will literally change his life. You see, he inadvertently reaches the Goddess Technical Help Line, and a goddess is dispatched to grant him one wish. The lovely young Belldandy informs him that he may have one wish - a wish for virtually anything in the world. In disbelief, Keiichi opts for a wish he believes will confound the system (and will prove that Belldandy has no particular wish-granting power): he wishes that Belldandy would stay with him always. The power of this wish almost rips the fabric of time and space but it is ultimately granted. But of course such a wish has unforseen consequences, including the fact that Keiichi lives in a guys-only dorm. When his roommates return to find him with a woman on the premises, he is immediately tossed out on to the street. But the wish also has other unexpected side effects - such as when Keiichi and Belldandy are in peril of being separated, a motorcycle is suddenly repaired so that they can travel together.

Sundome is the story of an apathetic young man whose dull existence is forever changed when an assertive young woman wants to join the same after-school club in which he is a member. If only all after-school clubs were as hands on as this!

An excellent and very educational series. About a newlywed couple who are virgins and their comedic ups and downs in learning how to have sex. Not really a hentai, though there are scenes which can be called hentai. Tastfully rendered taboo themes. A funny "how to" guide for sex illiterate and experts.

From Seven Seas: After millennia in hiding, Mina Tepes, the Princess of the ancient covenant and ruler of all vampires, wants change. Using the vast wealth of the Tepes line, she has paid off the entire gross national debt of Japan and in so doing, gained the authority to create a "special district" off the coast of Japan that is to become the future haven to vampires the world over! Now, on the eve of the landmark press conference announcing the existence of vampires to the world, terrorists and rival factions are plotting to assassinate Mina Tepes before she has a chance to make her world-changing announcement.

From here:
Growing older is pretty rough and Kenji is finding out just how hard it can be as life starts wearing down on him. On top of trying to make ends meet running a convenience store, he has to care for the niece that his missing sister left in his care. Memories of youth make it easier, until those memories come back to haunt you.

Kenji and his old friends are slowly being drawn into a mysterious conspiracy that could threaten the world. Who is the mysterious "friend", and how does he tie into Kenji's youth? Why are there disappearances and deaths tied into Ochanomizu University? The friend's memories hold the keys to the puzzle, but years between cloud the clues.

The strange occurances and the reach of the "friend" conspiracy grow by the day. It will all culminate on New Year's Eve 2000. Will Kenji and the rest of the group be able to put together the puzzle and save the world?

Note: The last two volumes of the story were serialized under the name 21st Century Boys and are not included here.

From Tokyopop:
In the horror of witnessing so many classmates perish before his eyes in a violent train wreck, Teru discovers two survivors in the tunnel: Ako and Nobuo. But salvation from this bloody carnage is far from their grasp. As they try to dig out from the wreck in order to come up with a plan to stay alive, the lack of light and food, combined with the stench of death and decay, will lead one member of the group down a dark and demented path. And with sudden, violent earthquakes shaking the tunnel, escaping to the outside world may lead them to an even greater danger...

Daisuke is a 23 year-old new schoolteacher. He ends up being put in charge of a 3rd grade elementary school class since the previous teacher quit, and in that class there is a girl who is quite a troublemaker--Rin Kokonoe. You could call her a masegaki (used to describe a kid that acts more like an adult in some ways), and she is also part tsundere (though more dere than tsun).

Was originally a one-shot in Afternoon in 2004 before it became a series in 2006. One day, a strange transfer student appears before Tsubaki. Urabe Mikoto is an antisocial girl, whose hobby is just sleeping during class-breaks. One day, Tsubaki goes to wake her up and accidentally tastes her drool... And gets hooked on that! After that, he starts going out with her and gets to know her better. Her second hobby, as it turns out, is carrying around scissors in her panties and cutting paper into flowers...

Yakumo Fujii was just like any other 16-year-old Japanese high school student. Well, his father did disappear in Tibet four years ago while searching for a legendary race of three-eyed beings, and Yakumo was forced to take a job as a waitress in a gay bar to support himself. But that was nothing compared to the strange girl Yakumo literally ran into one day on the way to work. She called herself Pai, and she carried a letter that Yakumo\'s father wrote just before he died. The note claimed that Pai was the last of the three-eyed race Prof. Fujii had spent his life searching for, a race with the power of eternal youth, the Sanjiyan Unkara.

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

A mysterious, lethal disease is on the loose worldwide, resulting in a catastrophic death rate of humanity, and the increasing rise of attacks, caused by the living dead.In Japan, several high school students and a school nurse have banded together to escape Fujimi Private High School shortly after it was attacked by "them." The group now attempts to figure who or what was responsible for this plague, and in the meantime, attempt to survive the present apocalypse.

Watanuki Kimihiro is a high school student plagued by yokai and ayakashi – spirits with a strong attraction to him. The spirits are invisible to others and encounters with them are extremely troublesome. When he stumbles into a shop that grants wishes, however, events in his life promise to become more unusual.

The shop is owned by Yuuko Ichihara – a mysterious and beautiful (sometimes playful) witch of many names and esoteric renown. For a price, she offers to grant Watanuki's wish to be rid of the spirits. The price, according to Yuuko, must be of equal value and so, as payment, he temporarily becomes Yuuko's part-time employee – a maid to be precise!

Watanuki's job also seems to consist of small errands dealing with the supernatural including the household chores. His love interest Himawari Kunogi, and "rival" Doumeki Shizuka, occasionally join him in his work as per Yuuko's request. The three become increasingly close despite Watanuki's annoyance with Doumeki.

Yuuko constantly refers to "hitsuzen", meaning inevitability, destiny, or fate, as being the driving force in the world. She states that there is no such thing as coincidence, and that every single action and decision is inevitable, because without them, other related events in the future could not happen.

Two twins, separated by fatal illness and a selective cure. Kasumi and her sister, Shizuku, were infected with the Medusa virus, which slowly turns the victim to stone. There is no cure, but of the two only Kasumi is selected to go into a sort of cryogenically frozen state along with 159 others until a cure is found. At some point in the undetermined future, Kasumi awakens to find herself and others who were in suspended animation in an unfamiliar world with violent monsters. Resolving to unlock the mysteries of her current situation and the fate of her twin sister, Kasumi struggles to survive in a treacherous world.

Continuation of Girl Saurus: Kanji was a normal student until the day he got confessed by a girl who beat him up after he rejected her. After he got beaten up , he gets some kind of phobia and a really disturbing one, he is afraid of women!!! To fight against his fear and to be able to protect himself he enters a boxing club, and you can imagine his reaction when he learns that all the members of this club are females, and more then that he meets the girl that beat him, who somehow transformed from fat and ugly girl into a gorgeous babe... [Anime-source.com]

Ever since he was a young child Sora Aoi had always exchanged words of "I love you" with his older sister Aki. Now, as he comes of age, he finds it much harder to exchange such comforts as they did in those simpler times. When Aki demonstrates her feelings toward him to go beyond a sisters love Sora finds himself questioning his feelings for his sister. Realizing their affection for one another they consumate their love in secret.  In a society that would never understand, they must now keep their love a secret from their family and everyone they know. With a boisterous twin sister and friends that want to be more than just friends, Sora will find it wont be so easy. Hormones raging, you can be sure that Itosugi Masahiro's "Aki-Sora" will be a sure-fire drama that you don't wanna miss!

Warning: Nudity and graphic situations!

Japan, 1995. After graduating from high school, Itō Kaiji moves to Tokyo to get a job, but he fails to find steady employment because the country is mired in its first recession since World War II. Depressed, he festers in his apartment, biding the time with cheap pranks, gambles, liquor and cigarettes. Kaiji is always thinking about money and his perpetual poverty frequently brings him to tears.

Kaiji's unrelenting misery continues for two years until he is paid an unexpected visit from a man named Endō, who wants to collect an outstanding debt owed to him in Kaiji's name. Endō gives Kaiji two options - either spend ten years to repay this outstanding debt, or board the gambling ship Espoir ("hope" in French) for one night to clear the debt. Using a con, Endō pressures Kaiji into accepting the deal, believing he will never come back from the voyage.
--Wikipedia

The manga is divided into three parts:
Part 1: Volume 1-13 (Complete)
Part 2: Volume 14-26 (Complete)
Part 3: Volume 27-39 (Complete)
Part 4: Volume 40-? (Ongoing)

Sakurakouji Sakura is a girl who appears modest and graceful but in reality is skilled in martial arts. After witnessing a boy burning people with his blue flame, she is startled to see that the same boy is a transfer student, Oogami Rei. Oogami is a Code Breaker, one who "does not exist". He is a seemingly cold-blooded killer who follows the principle of "an eye for an eye", to "use evil against evil". Convinced that killing is not right, Sakurakouji sets out to stop him and penetrate his icy heart.

New Series by Hiroki Endo, about a young man training in Shooto style MMA.

The Diclonius (two-horned human) are mutants created by humans. It has a special ability that can be described as a sixth sense. These mutants have enough power to exterminate the whole human race. Afraid of their powers, people isolate them in research labs to be studied.

Kanzaki Nao, an honest college student, who receives a hundred million yen one day, along with a card saying she has been chosen to take part in the Liar Game. The aim of the game is to trick the other players out of their hundred million yen. At the end, the winner gets the hundred million and the loser is a hundred million yen in debt. The next day, she receives notification that her opponent is her former teacher, Fujisawa Kazuo. She goes to him, seeking help, but ends up getting tricked into handing her money over. Desperate, she approaches the police for help, but they are unable to do anything. However, she is told of a mastermind swindler, Akiyama Shinichi, who is to be released from jail the next day. Desperate, she goes to him for help. (Source: D-Addicts Wiki)

A short story about a boy and a high school "encounter"...

The main character finds his possessions "abused" by some unknown person until he finally caught the culprit... masturbating to them?

2010, Seta Souji moves to the countryside to his uncle's house due to his parents working abroad. Not very friendly, he however manage to make a few friends there, and they all decide to solve the mystery behind the sudden cases of serial murders that strikes the area.

It is the spring of freshman year, and Kanji Sasahara is in a quandary. Should he fulfill his long-cherished dream of joining an otaku club? Saki Kasukabe also faces a dilemma. Can she ever turn her boyfriend, anime fanboy Kousaka, into a normal guy? Kanji triumphs where Saki fails, when both Kanji and Kousaka sign up for Genshiken: The Society for the Study of Modern Visual Culture. Undeterred, Saki chases Kousaka through the various activities of the club, from costume-playing and comic conventions to video gaming and collecting anime figures--learning more than she ever wanted to about the humorous world of the Japanese fan . . . (Source: Del Rey)

By the mangaka team of Akumetsu. Akira Inugami just transfered into his new school. The principal and teachers fear what may happen because Inugami was placed in the same homeroom as the schools biggest problem and gang leader. His homeroom teacher Aoshika is going out of her mind trying to figure out what happened the night before, where she could have sworn she saw this same Inugami beaten alive and then hit by a car by a large group of thugs in a park. But somehow, Inugami, who denys everything, of course, is alive and without a scratch attending his first day at his new school. What the teacher Aoshika did not witness was a crazy werewolf-like beast destroy the thugs that attacked Inugami in the park.