Genres

Based on the game by Age, sequel to MuvLuv Unlimited, taking place in an alternate universe where the Earth is invaded by aliens.

From Wikipedia:
In Alternative, Takeru wakes up three years after the end of Unlimited to find himself back in his room. Although he first thinks that everything that had happened to him was a dream, he soon feels that something is wrong, and leaves the house to find that he has been sent back in time to the beginning of the events in Unlimited. Unwilling to accept something like Alternative V, he decides to help professor Kouduki to complete Alternative IV and save mankind.

From Manga Pirate:
"Once upon a time, I was the fucking boss"

Choo, a middle-aged restaurant owner, is being ripped off by a couple of no good teenagers! They might think he's a nobody, but there is a past to him that nobody knows. And nobody should know.

Is he just a peaceful shopkeep, or is he something more than that?
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From Vendetta Scans:
One thing is for certain - if you exercise violence, that violence will return to you in any shape or form.

The man who bakes flour-based food and runs an eatery, has a darker past than anyone could ever guess.

...unless you see the name of his store.

Original Webcomic

From Girls' Generation:

After the death of his older brother, Shima has been left a mansion and a servant according to his older brother's will. There are two things Shima hates most in the world: being bossed around and being restricted. Both of which, his new servant, Haruki, never fails to miss. How will Shima deal with Haruki...?!

A bullied boy struggling with his depression possesses an unusual power to draw phantoms of evil spirit around him. Narrow-minded and timid, he has no hope for himself. Can he overcome the darkness that threatens to engulf him?

Author/Artist: http://tapastic.com/ruki

Who is that kid? Where did he come from? And why is he alone?

Alice's parent were killed when she was young, she saw the killer and made the promise to herself to kill him. Little did she know that when she will go to high school, the killer would become her teacher.

In Tokyo, an unchanging despair is lurking.
Mysterious man-eating beings, ghouls, run rampant in Tokyo. Living hidden during everyday life, the existence of ghouls, whose true identities are shrouded in mystery, permanently terrorizes Tokyo's residents.
At CCG, the sole institution that investigates and resolves cases related to ghouls, Haise Sasaki has been assigned a certain mission. While dealing with the unruly four problem children known as "Quinx", has Haise's days of suffering begun?

Between the mountains and the seas, there was a war with the beasts for survival. A man, named Bo Yi, discovered that drinking the beasts blood would grant him powers. Bo Yi traveled the world, recorded these beasts, and wrote the "Shan Hai Jing", he also established «Shang Hai Jing» city, to promote the idea of eating beasts to gain the power to hunt them. But when relations with other countries soured Bo Yi had dissapeared. Since then «Shan Hai Jing» started the pursuit of fame and profit.

A young man is a slave at «Shan Hai Jing», however, he has an astonishing ability. The battle with the beasts changed the fate of both this young man and the entire world.
(synopsis from SpookyPinata)

Original Webcomic
http://www.manben.com/mh-shanhainizhan1/

Everyone in a high school is suddenly transported to another world. As they are attacked by monsters they find that some of the students now have superpowers. They organize themselves into two groups. Those without powers are called the Stay Home Group and those with them are called the Exploration Group. On a day where most of the Exploration Group is out, the remaining ones that stay behind start the slaughtering and raping of the Stay Home Group. Here we meet our protagonist, an average guy with no abilities who had just barely escaped death at the hands of his schoolmates. He ends up far away in a cave on the verge of death, exhausted and wounded when a slime enters the cave and starts eating away at his hand. All he can do is utter, “…please… someone out there… help me….”

It has been five decades past since the beginning of a new era in a steampunk-inspired world where a group of nobles (who were all given complete authority by the Seven Engineers that founded the nation) terrorizes the local population by massively deploying automatons called 'Warrior Robots'. Nobody could stop them due to their obviously inherent supermachine strength/speed and thus the people have suffered for a long time under the nobles' oppressive rule. Well, that is the reality until a kind-hearted and brilliant mechanical engineer called Professor Genios and his son, Zeo with his very SPECIAL hand comes into the picture.

The story of how the infamous female Nine-tailed Fox came to be.

Its been 15 years after the last Great War. While the scars of wars appear to have vanished on the outside.In truth, the world has become a much harsher place.Follow the journey of Felix and Bay on their quest to find someone from their past.

Souzou Sagara, the commander of the Sekiho Army, is determined to overthrow the new government and change Japan. A young boy called Heihachi admires Sagara, and is determined to help him lead the country towards change.

Yui Kusanagi is the daughter of a Shinto shrine. She discovers a mysterious sword, which transports her to a different world where she meets the Greek god Zeus. He invites her to attend a school in a separate world that he created. Zeus intends to teach the meaning of love to the various young divine beings who also attend the school, in an attempt to reverse the weakening bond between humans and the gods.  (From: Wikipedia) Based on a visual novel by Broccoli under the same name.

Beings from a different dimension have started a war with mankind. To counter this threat, an academy called "Genetics" that trains female warriors called "Pandora," who can wield special weaponry and armor, was formed. Kazuya Aoi decided to enroll in this school because of a promise with his sister, an outstanding alumnus who died in battle. There he meets second year Satellizer L. Bridgette, nicknamed "The Untouchable Queen" due to her solitary demeanor but also top of her class whose battle simulation streak is undefeated, until he came... and slowly changed her. Colourized version/ Webtoon

A man who was once called the world’s strongest agent ended up becoming a teacher after his retirement, to train a new generation of agents. After many years of training his disciples, he was killed at the age of 60 by a secret organization’s ruse and was reincarnated in another world with his memories intact. Though he was surprised by the existence of magic and the strange species in that world, he quickly adapted to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his rigorous discipline, in order to reach his goal: Resume his career as a teacher which he left halfway through in his previous life. This is the story of a man, who, based on the memories and the experiences of his previous life, became a teacher who travels through the world with his students. Adaptation of a Light Novel.

University students shipwrecked and forced to board a deserted island with a serial killer.