From Yen Press:
The air of celebration surrounding fifteen-year-old Oz Vessalius’s coming-of-age ceremony quickly turns to horror when he is condemned for a sin about which he knows nothing. He is thrown into an eternal prison known as the Abyss, from which there is no escape. There, he meets a young girl named Alice, who is not what she seems. Now that the relentless cogs of fate have begun to turn, will they lead only to crushing despair for Oz, or is there some shred of hope for him to grasp on to?

From tethysdust at MangaHelpers:

Minaguchi Kaoru is nothing special. He's no good at sports or school, isn't in any clubs, and he's not popular. He has no friends and isn't even interested in any of the girls he knows. He's also teased due to the fact that he loves shoujo manga. Unlike the harem daydreams of his peers, he dreams of finding his true love. Unfortunately, a shinigami comes to kill him, simply because he's a "forever alone" sort of guy. When he gasps out his intention of embracing life with his final breaths, though, she takes it back! As long as he follows through on his intentions, he won't be killed.

To convince the shinigami that his plans are genuine, he declares that he will confess to the girl he likes, the very next day. Expecting failure with confessing to random girls in his school, he sends out love letters to four different girls. To his surprise, they all agree to be his girlfriend. Now, this shoujo-manga-loving guy has ended up in a kind of harem story, quadruple-timing four girls! Will he be able to stay involved enough with society to avoid an early death?

There is a Gothic-style mansion in a distant, rarely-visited part of Japan. There, the world's greatest surgeon, Naomitsu Madaraki, once lived but he hasn't come home in ages.
Instead, the professor's "daughter", Fran Madaraki, lives there with a large amount of her own ghoulish creations and her "younger sister" Veronica. She's a very unusual girl, what with the stitch patterns on her face and the giant bolts on either side of her head. Just as skilled at surgery as her father, and if you're willing to pay her price, she can do everything up to and including raising the dead. Fran believes that a life should be saved no matter the cost, and keep that in mind, since the results of her surgeries are rarely (if ever) pretty.

Spoiled rich girl Yao decides to join the Miami police force to enjoy car chases, gunfights and wanton destruction. The psychotic and not-too-bright girl is partnered with Lu Amano, the soft-spoken and sharp-tongued daughter of the police chief. Together the dirty duo clean up the streets of Miami and take on a mysterious crime syndicate known only as 'The Organization'.

From Yen Press:
At the invitation of an old school friend, introverted high-school student Mikado Ryuugamine, yearning for a life less ordinary, makes his way to Tokyo. His destination: Ikebukuro, a hotbed of madmen living most unusual lives. On his first day there, Mikado encounters a cast of characters so colorful, the rich hues of his rural hometown pale in comparison! And as if the naive stalker chick, the high school senior obsessed with the rather creepy object of his affections, the hikikomori genius doctor, the hedonistic information dealer, the strongest man in all of Ikebukuro weren’t enough…Mikado also chances upon a sight that leaves him rubbing his eyes and scratching his head — the Black Biker, who is black as night from bodysuit to license plate, soundlessly weaving through the streets like a figure out of an urban legend. Who is this “Headless Rider” on the jet-black metal steed!? And why does it seem like Mikado’s already gotten himself neck-deep in the insanity that is the norm in his new home!?

1st Arc: Durarara!! (4 Volumes)
2nd Arc: Saika Arc (3 Volumes)
3rd Arc: Yellow Flag Orchestra (3 Volumes)
4th Arc: Akane Arc (still ongoing)

In the 30th century A.D., in a world in which magic exists, 100 years have passed since the human race won a war against the Devil King. Even though the war caused many sacrifices, slowly but surely civilizations began to rise again.
One day, a virtuous child named Sai Akuto ("Worst Evil") is adopted from the orphanage he's lived in ever since a witch quietly left him at the church as a baby.
Five years later, Akuto passes the test to enter Constantin Magic High School. But after arriving and taking the vocational aptitude test, Akuto receives surprising results:
Examination Numbers: Number 021
Name: Sai Akuto
Future Occupation: The Devil King

About the lives of the sextuplets: Osomatsu, Karamatsu, Choromatsu, Ichimatsu, Jyushimatsu, and Todomatsu.

Note: Won the 10th Shogakukan Manga Award in 1964.

School girl is trained by a secret branch of the police to detect and to kill demons disguising themselves as humans.

After 10 years of training, Yoichi returns home to fight against the Wenkamui, an endless horde of mysterious monsters that threaten the safety of his village. He's not alone in his fight; his best friend Ryuu, drawer of the divine sword Kamui, has also spent this time training to fulfill his destiny. However, a decade is a long time, and upon his return, not everything is as Yoichi expected it would be...

[Written by MAL Rewrite]

What would you do if you were given the power to make your own rules in which everyone has to obey to them?

From Tokyopop:

Yume innocently uses her magic to help the people she encounters--soccer players, the wrongly incarcerated, or two young lovers wanting to see the moon on a cloudy night. And you can bet that Yume's magic leads to new adventures--and a few mishaps!

This is a 4-koma comedy about a young girl named Ichimatsu Kohina who got possessed by a low grade spirit called Kokkuri-san.

From MangaHelpers:
In this story set in the early 1920s, Tamahiko is the son of a wealthy family, but his life is changed forever when an accident cripples his right arm. No longer considered by his father as an heir, he is shuffled off into the country, to live out of sight. The teenage Tamahiko shuts himself in his new home, bitterly thinking of it as the place where he will die. One day, he learns that his father has 'bought' him a bride to take care of him, when the young teen girl named Yuzuki arrives at his door. She comes into his life like an innocent ray of sunshine, and Tamahiko's view of the world and his life starts changing bit-by-bit.

Jung Yoon-hwan may be an orphan but he was a college student who was focusing hard on his studies, one day he is brought to a mysterious "White room" to fight even when he does not want to. Every time he defeats these monsters he gains psychic power, magic, and items beyond his imaginations....

(Source: Game of Scanlation)

N/A

This is the tale of how Adachi Mitsuru went from being an assistant artist on a weekly manga to the superstar manga-ka we know him to be today. But it’s told (and written by) Mitsuru’s older brother Tsutomu, who was also an assistant artist early on in their careers…

From MangaHelpers:

In a strange twist on Arthurian legend, young Art pulls the magical sword Excalibur out of a stone--only to find himself as one of a million Arthurs, fighting to defend the island of Britain from enemies and to earn the rank of the true king. Art is pretty puny, but his childhood friend Ligu (who was also chosen by an Excalibur) tries to keep him from being immediately killed.

Soon Art lives in a castle with knights, which are created beings who serve the kings. From the respect with which he treats the knights, he inspires some to hope he becomes the true king. But is that really achievable by a scrawny crybaby like him? [tethysdust]

A new transfer student, Tae Yeob, on his first day in an all-boys school (though it is enticingly close to an all-girls school), stutters through introducing himself. He's awkward at first, but the other boys' snickering stops when he says with sudden calm, "My hobby is fighting. My goal for the future is to become an MMA fighter. I plan on crushing all this school's fighters by next week."

After collecting information about the various personalities and fighting styles of the top fighters in the school, he's ready to make good on his word. Ssen Nom, The Strongest Fighter, is an earlier work of the manhwaga of the God of Highschool, and it shows its lineage in bruises and blood!