If you're looking for manga similar to 8 Man After, you might like these titles.
Murdered by criminals, Detective Yokoda's body is retrieved by Professor Tani and taken to his laboratory. There, Tani performs an experiment that has failed seven times; Yokoda is the latest subject to have his life force transferred into an android body. For the first time, the experiment succeeds. Yokoda is reborn as the armor-skinned android 8 Man, able to dash at impossible speeds, as well as shape-shift into other people. He shifts himself into Yokoda, this time christening himself as "Hachiro Azuma". He keeps this identity a secret, known only to Tani and his police boss Chief Tanaka. Even his girlfriend Sachiko and friend Ichiro do not know he is an android. As 8-Man, Hachiro fights crime (even bringing his murderers to justice).
Continuation of Kamen Rider Spirits after the series changed magazines, Shin Kamen Rider Spirits follows the war between the evil Badan Empire and the 10 Showa Kamen Riders and their allies.
Takeshi Hongo is an expert motorcycle racer and a young genius with an IQ of 400. He is abducted by the secretive company Shocker and turned into a cyborg as part of a fiendish plot to take over the world. Just before his brain is irrevocably transformed, Hongo manages to escape his hidden prison with the assistance of his respected teacher Dr. Midorikawa, a scientific genius who has been forced to work for Shocker. Hongo, with his indomitable spirit and sense of justice, names himself the Masked Rider and uses his motorcycle, Cyclone, and the superhuman powers imbued in him by Shocker to combat the organization's evil ambitions!
After Japanese-American FBI agent Taki Kazuya and Kamen Rider 1 defeat a bat monster, they decide to contact the former riders including Stronger to investigate the appearance of monsters attacking them and civilians. Their investigation reveals the coming of an alien empire out to destroy the Earth, finishing the work that Shocker and other terrorist organizations have failed due to their defeat at the Rider's hands.
In their quest for the ultimate weapon, the secret organization Talon has delved into the realms of cybernetics and mind powers – culminating in the creation of the superpowered Blue Sonnet. When Talon begins to suspect that high school student Komatsuzaki Lan has level one Esper abilities, Sonnet is sent to observe and test her; but Lan has minimal control over her abilities, and when one of her friends is hurt during Sonnet’s “test,” she flees – with Talon’s forces hot on her trail. While Lan struggles to gain control of her newfound abilities and her humanity, Sonnet finds her own humanity slowly asserting itself. Will Talon succeed in molding Lan and Sonnet into the weapons they desire?
Cyborg 009 Conclusion - God's War is intended to be a proper conclusion to the original Cyborg 009 series.
A mysterious new hacker known only as the Puppet Master threatens to create chaos, erasing and rewriting the memories of his victims: humans who have cast away their physical body to become cyborgs. Is he an evil genius, or could he signal the beginning of a new age in the relationship between man and machine?