The Chrono Code, the key to a powerful weapon in the future, has been sent to 1994 and resides inside Ji Soo Jung. A gifted martial artist and the hope of her Kendo team in the upcoming national championships, Ji Soo Jung has no memory of her life prior to 4 years ago, and is searching for the lost brother she knows nothing about. She is catapulted into the middle of a violent struggle for the Chrono Code when different factions from the future start to fight over her, and she has no idea who is really a friend and who is really an enemy.

Once Demons and Humans were at war, and special warriors were needed to defend humans. Now a peace treaty exists between demons and humans. To uphold it human warriors now protect demons from other predatory demons. The Yosogi family is given this thankless task--and it's heir is young Akira, who can't even stand up against his older sister. But only Akira can sense the presence of demons, so he must become the next Demon Defender. But their grandfather has brought in a shy girl named Matsuri--and Akira is warned in a dream he must protect her at all costs!

From Dan of Population GO: Based off of The Song of the Nibelungs comes a manga about bravery, honor, and heroism. As the last of his people, Siegfried will stop at nothing until he becomes a legendary knight whose story will last eternity. If his legend lives on forever, then so will the memory of his people...and that is his sole reason for going on. 

It is the year 4088. It has been over one thousand years since the Crisis of Systems (Lost Property), which resulted in the destruction of four planetary systems, leaving only a single inhabitable planet, Zion. Mankind is forced to live in space colonies, since that one planet is constantly being invaded by alien life forms that have come to be known as Victim.

To stop the aliens and to allow people to land on Zion, mankind has developed the astronomical humanoid weapons, Ingrids, also known as Goddesses. G.O.A. (Goddess Operation Academy) is a school dedicated to the training of young men to pilot these Ingrids...

Set in 2194 AD, China, which is now a prosperous, super-modern country. The characters are mostly reincarnations of warriors from the 3 Kingdoms period. The story begins in Shin Yokohama with main chara Todoroki Ranshirou driving around & causing a ruckus with his bousouzoku called Yokohama Road Stars, when he gets a mysterious package from his father. Soon after he's attacked by Blades and makes an astonishing self-discovery... that he's the reincarnation of Sun Ce!

The much-awaited sequel to BLAME! follows a man, called a Dismantler, who is in charge of sub-dividing the nexus towers that incurr Safeguard interference upon its detection of humans without the net terminal genes. Although humans are once again able to reside in the Net sphere, the Safeguard are still a threat. The Dismantler or NSE, or Net sphere engineer, goes on a journey to aid mankind in their survival. NOTE: This oneshot is actually chapter 6 of Blame Gakuen! and So On

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.

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?

From Del Rey:

Since ancient days, the Gaius School of Witchcraft and Wizardry has trained the fiercest swordsmen and the most powerful wizards. Now one boy could become the greatest of them all. If he studies hard. If he is true to his friends. If he believes. And if he survives…

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.

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.

From Iskultrip Scans

Yamada Hana, a high school girl, woke up and found herself in a strange land after being enveloped by a bright light that came out from a mysterious book. There, Hana met a young man named Gentoku, and ended up staying with him and his army as "Koumei's disciple"…

From Tokyopop:

Three years after the popular video game The World was shut down, Tokio Kuryuu cannot wait for The World R:X to come out. Unfortunately for him, he forgets to reserve a copy and finds himself with no access to the game. That is, until a mysterious new transfer student forces him into the game and makes him her servant.

G.U.+ follows the player Haseo, a powerful PKKer known as "The Terror of Death". Haseo is obsessed with an infamous PKer known only as "Tri-Edge" who attacked a close friend of his sometime in the past. The manga details Haseo's search for Tri-Edge, and his eventual inclusion in a mysterious group known as "G.U."


Back story of the ps2 game (same title)
In 2015 a fire at the main CC Corp. building resulted in the loss of a lot of data, and The World was forced to shut down. By splicing in data from what would have been another game, CC Corp was able to rebuild the game system. The next year, "The World R:2" was released, but many old players objected because they were unable to bring over their old characters. However, many new users were drawn in by the new style, and over 12 million copies were sold. Though not a match for the previous version's 20 million users, it became the top-selling netgame on the market." As a result of the new world, four major clans (Kestrel, Lunar Tree, Canard, and Raven) came to power. The clans actions shape 'The World', and most players end up taking one side or another during conflicts.

.hack//Alcor takes place in the online game 'The World'. Nanase is a shy and naive girl belonging to the newbie helping guild 'Canard'. All she wants is to be with Silabus, the guild master whom she has deep admiration for. However, when the guild members are targeted by player killers (or PKs) from the guild Kestrel, will Nanase be able to brave the situation?

From Anime News Network:

A collection of short stories that look to mankind's exploration of space, and examine the possibilities that we could face when we decide to take those first fateful steps into the unknown.

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.

"Lured by the sweet fragrance of the flowers which blanket the earth, with fangs of steel and claws of iron, to the Garden of Eden which welcomed the ages, under the guise of a disaster from the heavens... seven dragons appeared."

Based on the game with the same name.