From Wikipedia:

An innocent young man, Ikuroo, has a parasite known as Baoh implanted in his brain by an evil organization, Doress. The parasite makes him nearly immortal and gives him the ability to transform into a really powerful beastie when he's in trouble.

Doress intends to use him in some sort of ploy for world domination. But while they're moving him around, a young psychic girl, Sumire (who's also being held by the organization), sets him free, and the two escape together. Of course, Dr. Kasuminome is the mad scientist behind the whole thing, and he isn't about to let his test subject get away... and he has everything from superpowered lackeys to a small army at his disposal.

Iori and Nachi are the "perfect pair" of the bodyguard agency Shelter. Partners since childhood, they bicker constantly, but when the latest mission threatens to separate them, is that really okay...?

Manga doesn't get much more noir than this. Benkei is just another expatriate Japanese arist living in the Big Apple. Or so it appears. As there "diabolical hard-boiled stories" show, surfaces aren't always what they seem. Flashbacks delve into sordid, secret past lives, and old scored, long festering, emerge without warning, asking to be settled.

And Benkei's secret? Maybe it's just that he's the only artist in town who isn't having fantasies of being a hitman-for-hire. He is one.

Bian Huang Ji, lying at the border of the south and north parties, is the only trade center where the rich and powerful people gather and illegal activities take place. In this place, laws don't exist. Whoever comes here is called Huang Ren (wild man), someone who doesn't belong to any kingdom or government. As there was no war occurring here, it's prospering and growing at an exceptional speed. However, war is like the ever-changing weather, it comes when you least expect it.

In the hopes of pleasing his childhood friend and crush, Chiharu, Arata agreed to help her clean out an old warehouse from her grandfather. But what neither of them knew was that the warehouse contained "tsukumogami", ancient objects imbued with life. When Arata accidentally broke the seal on a box containing an artifact that hungered for vengeance against humanity, Chiharu was kidnapped! Now it is up to Arata and the good, loyal artifacts to rescue Chiharu before it is too late!

Hundreds of millions of years ago, highly-advanced beings looking to make a planet for themselves purposefully tampered with Earth's natural processes in order to create multi-cellular life. Watching the planet's evolution closely, they continued to help life evolve further in the hopes of having actual civilization develop.
It's now 1996 in Seoul, where Hyesong, a high-school student, struggles with the usual problems of youth. The only unusual thing about him is that he's been having the same apocalyptic nightmare for an entire month; in the dream he is an great fighter and genius tactician who faces off against a seemingly-unbeatable foe.
Are these dreams not really dreams? Does he really have a role to play in the cosmic balance of the universe? And is the new girl in his class really just a normal student?

From back of book:

He-Sung has dreams of the Earth being destroyed by alien invaders! In these dreams he is a motorcycle-riding warrior, the last defense against the alien armada. By his side is a beautiful armor-clad girl with strange powers and futuristic weaponry. But these are just dreams, and they don't mean anything... right? That's what He-Sung thought... until his mystery dream girl appeared as a new student in his school! But if she is real... can the aliens be far behind?

The protagonist is your average, everyday, Korean school student. That is, if not for his obsession that aliens live on Earth disguised as humans.

Much to his surprise, he was right, the aliens play a game called "Avatar" where they take human form and live human lives. And because of a glitch he caused in their system, now his very life could be at risk.

Now he needs the protection of an Admin of the "Avatar game" or else he could very well die!

The "Dark Flower" is a sword of legend; a horrible legend of a gruesome slaughter three hundred years past. Lilia, a small girl from a village threatened by the bandit group whose leader has obtained this cursed weapon is now searching for help to save her city. Unfortunately, she is spotted by the bandits and can only run for her life. But, just as she is about to be caught, she runs into a young and seemingly weak traveller... is this coincidence? The Winner of the 14th Square Enix Manga prize.

From Tokyopop:

Daphne in the Brilliant Blue take place in a near future in which the remaining population lives in underwater cities, with waterways as streets. Years ago, while conducting underwater experiments, all contact with the surface was cut off. With the remaining human population now living underwater, The Deep Sea 9 Cities Association represent the last hope of mankind. Ai Mayuzumi is the daughter of the head of the research lab, and is an expert water jet bike driver. When the terrorist group Error, attacks the city, Ai becomes involved with the counter-terrorist group Stelnas, comprised of an all-female team, and led by a girl named Kei, and asks to join them. The group initially resists her efforts to join, but a surprising "gift" that Ai possesses, along with the way she handles herself during a kidnapping attempt, eventually sways the opinion of the members of Stelnas.

From Futari wa Pretty Anon:

Chino Houjo is just an ordinary high-school girl. But when her childhood friend Souma is suddenly attacked, she’s forced to purchase a ‘prince’ from the alternate dimension Albox to save his life. And now she’s got to go after the person who’s stolen Souma’s soul?!

A seminal history of Date Masamune. Yokoyama has a plain and matter of fact style for history without really trying to dramatize it.

The main protagonist is an Iga ninja named Saizou, who meets an Izumo priestess and protects her on her short journey to Sanada Yukimura. Sanada Yukimura is a powerful warlord in the Sengoku era. Sanada wants to gather 10 warriors, a party unrivaled in skill and power, to set his still secret plan into action.

This is an original story expanded from the STEINS;GATE game, and focusing on the heroine Amane Suzuha. In 2036, a monopoly on time machines has created world peace, but at the cost of human liberty.

Suzuha has followed in her late father's footsteps in fighting alongside the Valkyrie rebellion force to change the world. After the group fails on a major mission, Suzuha has almost no hope left. But then she discovers that her father left something for her: a time machine. Using this, maybe Suzuha will have the power to finally destroy this dystopian society and create a better present and future!

Sara Tanjuro just recently transferred to Mikagami Eruma's elementary school and have caused a major stir among the students. Tanjuro, knicknamed Satan, has been proposing his love to the girls left and right, something the shy Eruma would never think of doing. But Satan has a secret identity. He is a member of Michaela, a group of people who combine technology and exorcism to rid the world of angels that wreak havoc in society. As member number 666, Satan is an anti-angel specialist who has disguised the school supplies as weapons. He defeats supernatural beings with ease. Now if getting girls were that easy...

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]

Alternative world where Japanese culture kept its ground to this day and further. Protagonist, a female entertainer typical to Japanese traditional customs, finds herself swept into the world oh so familiar, and yet so different from the one she lived in so far.... a world where she has to fight to survive.

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

Sengawa's day job is as an accountant working for the police. But at night, he transforms into a ruthless assassin bringing death to anyone who deserves it. Those who have been wronged and whose grievances the police can't - or won't - listen to, turn to The Man With A Thousand Guns to avenge their suffering.

The year is 2028, location in New Koshigaya. A young boy, Isurugi Neru, lives in a poor family and is forced to quit school so that he can find his own way in life. Neru on the other hand, only thinks of one thing: to take revenge on Yagami, a classmate, who's especially gifted and has humiliated Neru numerous times.