Taken from Wikipedia and Dangerous Pleasure:
After being devastated in the third World War (known as The Third Division), Japan was divided in two. Several years after the end of the war, a crime organization called Vischio has taken control of the destroyed city of Toshima (formerly Tokyo, Japan's capital city), where they are holding a battle game known as "Igura". The main character, a young man named Akira, is falsely accused of a crime. Once arrested, a mysterious woman appears before him, offering him freedom if he agrees to participate in Igura and defeat Igura's strongest man: the king, or "Il-re". The story follows Akira's life in the harsh, lawless Toshima as he fights both to survive and to unravel the mysteries developing around him.

From Esthétique:

Kosumo has a serious medical condition that has kept her in the hospital ever since she was a child. Since Kosumo's blood type is rare, it impossible to find a donor.
While Kosumo is on the verge of death, out in the city, the 99th Generation Miko, Himiko-sama, gets into a terrible accident while trying to save a child. She is rushed to the hospital, and there her fate crosses with Kosumo's.
When the hospital discovers that Himiko has the same rare blood type as Kosumo, they decide to make her a donor, since Himiko is sure to die as a result of the accident. Kosumo recovers and moves back to Tokyo, but later finds out that Himiko's blood isn't the only thing flowing inside her…

The beautiful and prosperous ancient land of Terresia is being destroyed by the Devourer, a demonic creature from another planet. The World Tree, which created and protected this magical land, is wasting away from the Devourer’s continuous attacks. The World Tree uses what’s left of its strength to call on the world’s last hope in a dark battle of survival – you.

From iskultrip Scans:
Due to the influence of the "Dragon veins", some young men and women awoke as "those with power". They'll discover their "star of fate" in a struggle to the death with the "oni" attacking Tokyo!!! The super popular action anime has become a fantastic comic!!

A Mercedes-Benz SLR car ad by Go Nagai featuring Devilman.

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On a remote island, a skilled swordsman who honed his craft on the local population attempts to atone for his sins and lift a curse by hunting and killing demons.

Winner of the Hagio Moto Special Award for manga.

Original webtoon

The story of Tachibana Reiji and Tachibana Ayaka continues.

Unknown beings across from the city’s neon lights, preying on you. Do not fear. There is the Beast!

A 16 years Old Girl, Deb, lives with her mother and her two siblings because her father has left the house, when Deb was around eight. Eight years now, her family and she, move out to a new town. She thinks that her family hides something important from her. At the new town, Deb goes to see her sister, Kelly at her new job, but she faces a bunch of strange, deformed men. Suddenly, a man appears and saves her from those creatures, saying to her that maybe, they'll meet again...

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In a world where once you turn 14, a crystal emerges for your body, and from that crystal a beast blade is born.
Beast blades are your lifetime partner and there are many different types of them which can be used to accomplish all sorta of tasks.

The story follows Soluto, a student at Nenokoku middleschool and his beast blade El Cid.

Hachiouji Tarou is an average 2nd year high school student. Since his father died, leaving him as the head of the family, he’s been constantly pulling his brother out of trouble. One night, when he came back home, his mother's head was rolling on the floor, and an evil spirit had hold of his younger brother. Instead of helping him, he hesitated and stood frozen with fear while the spirit got away with his brother. Now Tarou is on a quest to find his brother and exterminate evil spirits.

Based on the visual novel of the same name. In 1986, between October 4th and 5th, members of the Ushiromiya family gather on the secluded island of Rokkenjima to discuss the division of the family's massive fortune upon the impending death of the family's head, Kinzo. However, when a typhoon traps the eighteen people present on the island, six people are mysteriously murdered. The remaining people struggle to survive as the murders continue, supposedly by the will of the legendary Golden Witch, Beatrice.

Other manga:
+ Triage X manga
+ Sidonia no Kishi manga

The manga centers on Poro, a demon from the underworld who comes to the human world.

From MangaHelpers:
After a terrible earthquake, Satoru wakes up in a pitch black cave that him and his friends were exploring. Desperately moving through the crumbling cave with just his backpack, he expects a warm rescue once he gets out. But what awaits Satoru was an unbelievable fact: Japan has sunk underwater due to the earthquake and he is stranded on an island with no one to help him. Can Satoru learn how to survive by himself?

What's a guy to do when a militant girl demands he date her little sister? Crazy right? Well, it's exactly what happens to transfer student Kakizaki Kokera. The Harimoto Sisters have a strange love-hate relationship he just can't help but get dragged into. And what's more, there's a strange town legend about a middle schooler who cleaned up the town with overwhelming violence five years ago called Urooboe Uroboros (Half-Remembered Uroboros).

When a genius manhua artist enters the world created byhis own pen, where humans and fantastical creaturescoexist, he is determined to become the god reigning overthis world. However, things are not as simple as he thinks.Will he become the god of this world, or will he only barelyscrape by to survive?