In 2071, north pole ice have melted and the land has been submerged. Humanity survived but it's divided into two species: the true humans, those who live in underwater cities, and the Dugons, those who chose to undergo genetic modification to live in the sea. Both species go to war to survive as long as the Dugons consider the humans good to eat.

To defend against the Dugons, the city of Mari Ramelle builds a new kind of weapon, the mermaid robot, Salacia. Because of the small size of the the pilot cabin, the robot is piloted by a girl and a boy, both 13 years old: Marin Yuuki and Ushio Mizushiro. The fight for survival is hard, and during the manga, the city builds more mermaid robots.

(Source: MU)

Honey Kisaragi is a normal catholic schoolgirl. That is, until her father was murdered by the Panther Claws who were seeking the Airbourne Elemental Fixation Device. She then finds out that she is actually an android created by him with the Airbourne Elemental Fixation Device within her. She is now trying to live a life as a normal schoolgirl and seeking revenge against Panther Claw.

Although I am a big Devilman fan, and have read a couple volumes of Amon, I am not 100% sure how it ties in with the Devilman continuity. So what I will do is summarize Devilman, and then review Amon. Beware, this review will contain Devilman spoilers, it would be pretty hard to write this without them. Devilman is the story of Fudou Akira, a timid, bullied teenager who is living with his friend Miki due to his parents being away. (They are archeologists.) One day, Akira's best friend, Asuka Ryo tells him he has something urgent to tell Akira and takes him to his house where he explains that demons once ruled the world but were frozen during the ice age. For a long time they were trapped, but now many of them have been freed. Ryo tells Akira that the only way to combat the demon threat is to unite with one. Furthermore, demons can only be controlled by a person pure of heart. Therefore, Akira must unite with a demon to become mankind's savior. With Ryo's help, Akira is able to unite with Amon (Hell's god of war.) and he becomes Devilman. OK, now fast forward to Amon. (Here come the Devilman spoilers.) Miki is dead. Akira's precious friend was killed by the very humans he was protecting. Ryo was actually satan - in human form. The trauma of Miki's death causes Akira to fade into himself and this allows Amon to take over. At the same time, it seems that satan has initiated the apocalypse. (There is this goup spreading from Japan throughout the world, melting/absorbing people.) satan works to bring the demon race under it's(?) (...satan is a hermaphrodite. I can't say "his" or "hers".) control as they run rampant, killing people. The human race, facing the demon threat has entered into martial law and chaos, frequently killing each other even. It seems the world is headed for destruction, and Akira's friends Dosu 6, Mericou-jin (I think I spelled that wrong.), and Miiko along with some other unidentified psychic figures, try to restore Akira's consciousness. While all of this goes on, Amon has only one thing in mind - killing satan. If you can tolerate the violence and demonic themes, Amon is a solid story delivered by the pen of the great Go Nagai with excellent art by Yuu Kinutani. It's not for everyone, but I recommend it to all who are confident they can handle it.

After the world ended in the original Devilman, Akira Fudo is in hell, seeking the soul of his beloved Miki while at the same time Doctor Hell is beseeching the underworld for power in order to get his revenge upon the hated Mazinger. Akira sets in motion a chain of events that earn the enmity of Hades himself, who'll stop at nothing to avenge the slights Akira commits against him...

Continuation of the successful manga and anime series Mazinger Z, Great Mazinger starts after the defeat of Mazinger Z. Tetsuya Tsurugi is the new protagonist, piloting the powerful Great Mazinger, a creation of the once thought dead Kenzo Kabuto, the father of Koji Kabuto. This time the enemy is the Mycene Empire and its powerful robots. (manga updates)

In this story, Nagai gets his folklore on with every chapter containing a lot on Buddhist lore or Japanese folklore. The prologue introduces us to Heaven, Incorporated, a company with a particular staff that hunts down all sorts of supernatural monsters and protects humanity from them.
(Source: MU)

Lovely Angel is about a beautiful woman known for her kindness, charm and ability to touch the lives of others....through some unconventional means.

(Source: MU)

A shocking and violent look at a post apocalyptic future. Many different stories centre around an array of characters dealing with life in this desolate world. All the stories feature a huge man named Jack who is in an ongoing battle with a villain named Slum King.
(Source: ANN)Note: This is kanzenban version which consists of: 7 volumes (published by Kodansha) and 31 volumes (published by Nihon Bungeisha) merged into 18 volumes.

In the prehistoric times when men were reptiles and the world was over-run with dinosaurs, humanity was threatened with war. The humans are fighting against the almighty Gor to return peace to their world.

Mazinger Angels chronicles the adventures of four women who pilot giant robots in the Mazinger vein. The concept is a spoof on the late 70's and early 80's popular TV series Charlie's Angels.
Three of the robots, Aphrodite A, Diana A and Minerva X are from the original Mazinger Z series, while Venus A is from the Great Mazinger series. Their pilots are also traditional characters from Go Nagai's universe, Sayaka Yumi and Jun Hono from Mazinger Z and Great Mazinger respectively, and Hikaru Makiba and Maria Fleed from Grendizer.
The style of the manga highlights the sex appeal of both the characters and the mechas, sometimes similarly to the way Aika's female characters are shown.
(Source: Wikipedia)

An autobiographical manga about the career of Nagai Go and how his most known works were born.
How a young Nagai Go, struggling to break out of his typecasting as the go-to guy for gag manga by breaking into the sophisticated world of story manga.

A Violence Jack one-shot from 2001. What happens when Jack and some bikers mysteriously get sent back into the age of samurai.

Young sports enthusiast, Yamato Hino hears voices calling out to him and during a thunderstorm, he is brought to a parallel world. In this world is the Kingdom Mu, under attack by the evil Dorado of the Empire of Dinosaurs. Yamato was summoned from the prayers of queen Aila Mu to pilot a statue known as the God Mazinger. Joining the Mu army's ranks, Yamato fights against Dorado and his army.

(Source: Mazinger Wikia)

The great demon Mao Dante, exploiting the weakness of a boy exposed to his demoniac influence in the dreams, is awakened from a thousand years sleep.
The will of this being, a survivor of an ancient and forgotten civilization , is to wipe out the whole human race.
Anyhow nothing is so simple: the motivations of the demon aren't so wicked as one could think and they will combine with the life of the boy which hangs between nightmare and craziness.
In the meanwhile the satanist will fight against the hierarchy of the church to obtain a justice which is, as it's easy to guess, that of the demon Mao.
This series didn't have an ending until it's remake in 2002. Nagai took many ideas from Mao Dante into Devilman. (mangaupdates.com)

Set in 2025, a roboticist named Fudou Yuuki joins a project involving a large mural depicting humanity's true past as well as the ancient but advanced technology found in Antarctica.

(Source: Devilman Wikia)

Akira Fudo, who has become the Devilman, the only being who can fight demons; a being possessing the powers of a demon and a soul of a man.

A long time ago, the Earth was ruled by demons. The demons constantly fought each other for survival, but soon found themselves fighting a new race of beings: The first humans. The demons then became imprisoned in ice after a great cataclysm. They would remain there until the ice melted, after which it was said Satan would rise and lead them in Armageddon. That time has come in Go Nagai's Devilman.
source wikipedia

Mazinger, later called Mazinger U.S.A. Version or Mazinger U.S. Version to avoid confusions with the rest of the Mazinger works, is a 58 pages long manga created by Go Nagai specifically for the US market. It features full-color graphics, text in English and left-to-right formatting. It is partially inspired by Gulliver's Travels.

A short manga version of the UFO Robo Grendizer anime. Released along the anime series, UFO Robot Grendizer follows the adventures of Duke Fleed, the prince of Planet Fleed, who, disguised as Daisuke, a farm worker, fights against the forces that destroyed his planet, the Vegan Empire, also the creators of Grendizer that Duke stole to fight them. While not originaly considered part of the Mazinger series, Koji Kabuto and the Mazinger mechas appear in this series, making it sort of a sequel. Grendizer introduced the concept of a transformable robot and a space mecha, concepts that were later taken into other mecha series. It was extremely popular in Japan, Canada, France, Italy, and the Arab world and has a strong following in those countries even today.