Since the beginning of time ninjas have been regarded as people with great skill and power, the Blazing NinjaMan (Shinobi Mantaro) is one such young man. There is only one problem, the era of the ninja has come and gone. How can Shinobi consider himself a ninja in modern day Japan (1990s) and survive the daily rigors of high school life.

The story revolves around Tsunashi, the child of royalty who was left behind in the lost kingdom of Karan. He is expected by those around him to awaken his great powers that sleep within him in order to revive the kingdom — but rather than fighting, Tsunan enjoys playing in the world of books. However, he must become serious soon, as a new army is threatening to invade Karan.

From MangaHelpers:
Yasaka Tokiwa lives in an unusual time, and according to his dreams, it's about to become even stranger. He's been having a dream of a woman called Ri'in ever since the robot, who he calls Makina, came to his home. He and Makina attend the same school, where their other classmates include a secret ninja (Kusanagi Kanata) and a sorcerer (Yata Haruka).
When Tokiwa, the robot, the ninja, and the sorcerer rush to rescue the student council president from a demon, the boys find that they've all been having the same dream! What is going to happen to their world?

At a boarding girls' high school where every student is an assassin, they target only one life: "The Hare", who appears to be a girl named Ichinose Hare. Similarly, "Azuma Tokaku" is an assassin who transferred schools to target her, however she gradually became attracted to "Hare" and decided to protect her.

Extreme school life START!

Inuyashiki has a family, a wife and two kids, none of which care about him. When he learns that he has only three months to live he realizes that the only one who will miss him is his dog. Shortly after this realization he is killed in a crash landing by aliens. He is rebuilt by them as a machine with a human exterior. How will his life change now that he isn't human.

Humanity's peaceful days all at once transform into an unspeakably odious hell.
The sudden invasion of wasp-like insects, along with gargantuan "dolls" wielding their enormous alien weapons, annihilating everyone in their path.
In the middle of the chaos, high school first-year, Iruma Ikaruga, fights to save his best friend and his beloved senpai from the dolls' assault with an unyielding spirit.
However, all that awaits him is despair.
Just what are the enormous puppets known as "Dolly"after?
What fate awaits Iruma?
The curtain has risen on humanity's "puppet show" of unimaginable despair, and the battle for survival has begun.

From: Easy Going Scans

A continuation of Brave 10. 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.

One social outcast unleashes a cross counter that will change the world! A raging storm of fighting action!

Shotaro Mitarai has given up on life, but when he visits the great forests of Mt. Fuji to end it all, he's attacked by the Suicide Hunters. On the tip of a gruesome lynching and faced with a tragic death, the seeds of rage sprout within Shotaro! What course of action will he take from within the inferno of anger?!

Awaken! Stand and fight! Let the gong of your soul sound true!

The spin-off of the popular fantasy manga "Fairy Tail". Consists of 3 volumes

Volume 1: Kengami no Souryuu / Twin Dragons of Sabertooth
Sting, who became the master of Sabertooth, Rogue, Yukino, and Minerva together perform jobs together, but...? What is the danger approaching their guild and the whole continent!? The episode that was not shown in the original story is now being told!!

Volume 2: Rhodonite / Road Knight
Spin-off of Fairy Tail following Gajeel and his past.

Volume 3: Raigo Issen / Flash of Great Lightning
The story centers Laxus Dreyar, the Thunder God Tribe, and the time they were affiliated with Blue Pegasus.

From Manga Box:
One day, a yakuza gang member is attacked in Roppongi, Tokyo. This is only a prologue to one man's revenge story, triggered by the events of twenty-two years ago. The flames of revenge burn in the darkness of the city. By the author of Hitoshi Tadano, Chief of Special Operations, Kimio Yanagizawa.

Tegami Bachi (or Letter Bees) are couriers that deliver important letters and packages throughout the land of eternal dusk, Amber Ground.

The story revolves around Lag Seeing, a young boy who was born on The Day of Flicker, 12 years ago when the man-made sun went down for unknown reasons. The manga follows his ambition to become a Letter Bee and how he follows the path of his idol Gauche Suede who suddenly went missing one day...

A rising boss in the underworld is forced to lead a double life as a police officer and a gang boss in order to find the killer of his brother.

Completed printed version
Author remade the series at Lezhin

Lezhin Publication

Misaki Hayato returns to his hometown and enrolls in the same high school as his two childhood friends. A lot has changed in the years he has been gone, his former best friends are seemingly distant from each other and leading relatively normal high school lives. Hayato's sudden arrival soon changes that and sends shockwaves through the entire town's delinquent population with his willingness to do anything for his friends and his love for a good fight.

Even if people are born with super powers, they must serve as sidekicks of superheroes in order to become superheroes themselves. Lamia a.k.a Dream Girl has the power to make people fall asleep. She is the sidekick of Darkslug, who is not a great hero compared to his reputation. One day, Dream Girl and Theo work together to get rid of villains and save the world.

Murakami Sho has been putting years of blood and sweat into G&G Gold, a large banking company. He came up from nothing, worked insanely hard and now lives very comfortably, even having Rei, the hottest girl in the company, as his girlfriend.
But all that starts to slip away when Kirishima Joe comes into the company. With his handsome looks, impeccable style, calm demeanor and well endowed manhood, Joe has been upstaging Sho in every aspect of his life. And when Joe takes Rei away from him, Sho snaps and takes any measure to destroy Joe’s life. But Joe has a secret that makes him hard to break.

Plants have taken over the planet.
In 2017, the vegetation in Tokyo rose up and toppled human society in moments.
The few survivors are forced to live in the relative safety of a subway network, but supplies are running low.
Join an average high school student named Akira as he challenges the plants in a struggle for survival!

"Three years ago, he had the same posture.
Three years ago, he had stood behind Miyuki.
Yes.... Compared to three years ago, it had changed."

Set three years prior to the present time, Tsuioku Hen tells the events that would change Miyuki's world drastically, as well as the events that led Tatsuya to become what he is now.

(Adaption of Light Novel v08)

A year has passed since the Demans took over the island. The humans await a savior. A tale of a crimson knight that appears before them.

After a mission gone awry, the doubtful main character, Rood, is sent to a famous magic school, Helios. Here, he must protect an important person's son who has a very bad time at the school.

Iori is a high-school girl who doesn't know what she wants to do with her future, and tends to run away from things. One day, she is attacked by strange dead-eyed people on her way to school, only to be saved by an equally mysterious long-haired man. Later that day, her friend at school, Jion, seems to fall under the same murderous influence. To her surprise, she finds herself capable of defending herself from his violent attack. Afterward, the long-haired man she met in the morning, Zerozaki Soushiki, arrives once more, this time to invite her to become his little sister. What has Iori become involved with, and will she be able to survive this change to her life?