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

Takaya, Yoshiki

Sho and his friend, Tetsuro, stumble upon a strange orb-like mechanism, the Guyver Unit, in the woods. It physically bonds with Sho and turns him into the alien soldier, Guyver. His mission is to protect the Guyver Unit from the Japanese corporation known as Chronos. They are after it and two other units just like it. To retrieve the object, they send out vicious monsters known as Zoanoids. So no one is safe in Sho's life; not even himself.

Kyoushoku Soukou Guyver

Bio-Booster Armor Guyver

強殖装甲ガイバー

Ishinomori, Shoutarou

Cyborg 009 is the story of a half-Japanese juvenile delinquent, Shimamura Joe AKA 'Cyborg 009.' 'Black Ghost,' a top-secret organization bent on promoting global warfare, kidnaps Joe along with eight other unwanted members of society from the four corners of the world and turns them into cyborgs. Though the organization intends to turn the group into super-powered killing machines, it's not long before Joe and his new companions rebel against Black Ghost and make their escape with the help of an old scientist.

Once Joe and friends have freed themselves, Black Ghost sends a series of other cyborgs and giant robots in hot pursuit. Using their new powers and abilities, our heroes stay one step ahead of Black Ghost and its evil machinations, but can they save the world from its diabolical scheme?

(Source: Tokyopop)

Cyborg 009

サイボーグ009

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

Ryuu stows away on a space vessel, only to be found by the crew when it's far to late to return to Earth. So they stick him in a spare sleep capsule instead. Things take a turn for the unexpected, however, when Ryuu wakes up to find himself the sole survivor of the expedition, the spaceship having crash landed on a grossly mutated and wholly unfamiliar Earth.

Joining forces with fellow survivors from a different crash, Ryuu and his comrades fight to survive on this new and deadly Earth as they search for any humans that might have made it through the mysterious apocalypse.

(Source: MU)

Ryuu no Michi

リュウの道

Matsumoto, Leiji

Emeraldas navigates the sea of stars—and swears to do so until the flame of her life is extinguished. Aboard her ship, the Queen Emeraldas, she sails in search of a certain object, and along the way encounters the passions and tragedies of those who dare brave the infinite reaches of space. 

(Source: Kodansha Comics USA)

Included one-shot:
Volume 4: Emeraldus Versus Herlock

Queen Emeraldas

クィーン・エメラルダス

Yokoyama, Mitsuteru

Dr. Kaneda was developing experimental giant robot warriors to fight the allies during the Second World War, but before his creations could see action, Allied bombs destroyed the facility and killed him. A decade later criminals discovered two of the surviving prototypes, #26 and 27 in the series, and used the remote controlled robots to commit a number of crimes. Young Shotaro Kaneda, the twelve year old son of Dr. Kaneda, did some investigating and discovered that the mob were hunting for the twenty-eighth robot in the series, rumoured to be the most powerful of them all. Racing the villains, Shotaro discovers the robot first, along with Dr. Shikishima, a colleague of his father who was also believed to be killed by the Allied bombing. Together the two prevent Tetsujin 28-go (the robot's official designation) from falling into the hands of the bad guys and decide to dedicate him to peace rather than war.

Tetsujin 28-gou

鉄人28号

Minagawa, Ryouji

Takashige, Hiroshi

An ancient alien civilization once hid artifacts of immense power across the Earth, and now the world's governments will stop at nothing to seize those relics for their own nefarious purposes. Only the ARCAM corporation stands against them, whose special agents, the Spriggan, are the world's last line of defense against the alien doomsday weapons. Equipped with experimental armor that grants him unmatched strength, Yuu Ominae is Spriggans' ace operator, sent to avert catastrophes around the world.

(Source: Seven Seas Entertainment)

Spriggan

SPRIGGAN

The manga version of the live action Robot Keiji tv series.

The story is about a robot named Robot Detective K dressed in a human Detective outfit fighting kaijin.

Robot Keiji

ロボット刑事

Akiyama, George

Nine children are bestowed the almighty power of the monstrous robot, The Moon. By focusing their thoughts together they become able to control it with their minds and save the world from annihilation.

The Moon

ザ・ムーン

Hara, Tetsuo

Mitsui, Ryuichi

We are in year 2035 on the Tinos planet, colonized 300 years before by some earthlings. With only half of Earth's oxygen concentration and with cold arctic conditions over most of Tinos, the human beings are forced to wear a life support apparatus that supplies the oxygen necessary for survival. The black market in such apparatuses is a flourishing business in the criminal world of Junk City.

Blue, the protagonist, is in desperate need of a life support system after being mugged, but an unscrupulous bunch of criminals cheat him of his money and leave him with an outdated model with an old AI. He is tricked by the head of the police, Weiser, into a committing murder, and is then killed himself. The AI, called Fatso, decides to save his life, and gives him a new artificial body filled with extraordinary strength and the cumulative knowledge of their combined three hundred and seventeen years. The resurrected Blue decides to get revenge and protect all those suffering under the tyranny of Weiser.

Manga Like Genshi Shounen Ryuu