Nagai, Go

Soft-hearted Akira Fudou has always been somewhat of a pushover. When he reunites with his childhood friend, Ryou Asuka, in a fateful encounter, Ryou reveals to him the terrifying reality of his father's research: demons exist and are planning to claim possession of the earth once again.

Eager to help his friend save humanity, Akira agrees to attend Black Sabbath, a party filled with depravity and corruption, to attempt to merge with a demon. A near-death encounter causes him to unify with Amon, a demon feared amongst even his own kind. Together they form Devilman, a combination of Amon's strength and Akira's pure heart.

After uniting with Amon, Akira begins to fight against the demons with his newfound power, desperate to stop the downfall of all human civilization.

[Written by MAL Rewrite]

Devilman

デビルマン

Adachi, Mitsuru

The story is set in a place very similar in appearance to Earth in the Edo period. However, Adachi (the mangaka) regularly reminds the reader all throughout the series that the setting is another planet in the distant future which just happens to look like Earth.

After the death of his mother, Shichimi sets out to join his step-brothers and -sister who live together in Karakuri Tenement, a place provided by the father they have never met. He finds out that each of them had different mothers (all of whom have died), but were fathered by the same man. Not long after Shichimi's arrival, the siblings decide to journey to visit the graves of each of their mothers. On this journey, they encounter many dangers.

(Source: Wikipedia)

Nijiiro Tougarashi

虹色とうがらし

Manabe, Jouji

It`s face-to-face confrontation when Kahm stares down her father and refuses to end her relationship with Tetsuya. In retaliation, her father sends a punitive fleet to Earth -- with orders not only to crush the rebellion but to annihilate the entire solar system!

(Source: Amazon)

Outlanders

アウトランダーズ

Shirow, Masamune

The main plot revolves around the Yamata Empire's plan to destroy all the galaxy's negative karma  using a massive technological reactor called the Nāga Generator. Unfortunately, negative karma cannot simply be destroyed, it must be atoned for. However the leader of the powerful mystic Buddhist Fuze Clan plans to stop the destruction of the negative karma which will end up creating the nine-headed Nāga and destroy the world if not the whole universe. To help in stopping the creation of the Nāga, the clan summons a Shinto god known as Susano, the Warrior God of Destruction. The powerful, arrogant, and homicidal god faces challenges. These include the Empire and the clan leader's own daughter, the bratty sorceress Seska, who is possessed by the power of the negative Karma and a powerful magic formula.

(Source: Wikipedia)

Senjutsu Choukoukaku Orion

Orion

仙術超攻殻 ORION

Iwata, Kazuhisa

Something monstrous rises up from the sea and nearly sinks a Japanese fishing boat. The sole survivor tells a tale that no one wants to believe. 

But when a Russian nuclear submarine is destroyed in the same waters, the world is forced to face the truth: Godzilla has returned! This manga classic was originally published by Dark Horse in black and white in 1988

(Source: MU)

Godzilla

ゴジラ

Kobayashi, Tatsuyoshi

After a terrorist bombing takes the life of his only daughter, reknowned bio-geneticist Professor Shinigami merges her cells with those of her favourite rose in life. When the rose is almost destroyed in an earthquake, he also bonds Godzilla cells, which the Japanese government gathered for study after The King Of The Monsters last raid on Japan, to the plant to make it immortal.
The same terrorists want the G-cells, and threaten to unleash Godzilla once more if the Japanese government fails to give in to their demands.
Soon, Godzilla returns and makes his way towards the genetically altered plant, which has now mutated into the colossal horror called Biollante!

Godzilla vs. Biollante

ゴジラvsビオランテ

Miyama, Noboru

"Put an end to this cursed world! That is your fate!" An alchemist by the name of Godot whose father was charged with theft must seek revenge for his father and his own freedom as he participates in the fighting festival known as Valhalla.

(Source: Kodansha, translated)

Godot

ゴドー

Sakai, Takayuki

Time-travellers from the 22nd century return to present day Japan to warn the world that Godzilla will soon return, and his rampage will be so great that the country will never recover. With the help of a non-fiction writer who has accurately guessed the true origin of Godzilla, the people of the future offer to return to the past and prevent Godzilla's birth. However, upon returning to the present they find that Godzilla has been replaced by an even greater threat; The three-headed demon King Ghidorah! How can the world survive without the King Of The Monsters to face this new terror?

Godzilla vs. King Ghidorah

ゴジラvsキングギドラ

The future when humans live underground in order to escape radioactivity after the nuclear war.

ESP people who sometimes come into existence were called "P" that meant "Perplexer", evaded and persecuted. 

Stella tries to notice her son's Srow is P and to commit suicide with him. 
However, only Srow survives, and he is taken by Yang who is a close friend of Stella.

Yume no Hate

The end of the dream

夢の果て

Oze, Akira

Yajima, Masao

After having vivid daydreams of a barren and far off world, a teenage delinquent finds himself transported to this world after a near fatal accident.

Ryuu

リュウ

A collection of short stories, most of which follow the adventures of the one-eyed female mercenary Khada.

Dora

ドーラ

Miura, Kentarou

Studio Gaga

Guts, a former mercenary now known as the Black Swordsman, is out for revenge. After a tumultuous childhood, he finally finds someone he respects and believes he can trust, only to have everything fall apart when this person takes away everything important to Guts for the purpose of fulfilling his own desires. Now marked for death, Guts becomes condemned to a fate in which he is relentlessly pursued by demonic beings.

Setting out on a dreadful quest riddled with misfortune, Guts, armed with a massive sword and monstrous strength, will let nothing stop him, not even death itself, until he is finally able to take the head of the one who stripped him—and his loved one—of their humanity.

[Written by MAL Rewrite]

Included one-shot:
Volume 14: Berserk: The Prototype

12 Manga Like Nano Machine