If you're looking for manga similar to Shin Kamen Rider Spirits, you might like these titles.
One day high school student Hiro decides to apply as a monitor for a new gadget called JUNK. Soon he recieves a strange looking device in the mail. Upon activation, Hiro is encased in a powered armor JUNK suit granting him incredible strength, speed and agility. However, Hiro's repeat abuse at the hands of the school bullies leaves him hungry for revenge... not super heroism.
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).
Shuto Katsuragi is a superhero otaku. Only problem is, he's too short and always getting teased for his height... especially when he tries to emulate his favorite superhero! To make matters worse, Shuto suddenly gets abducted and tricked into participating in some rather sketchy and super-villainous experiments! What's a shrimp to do when his dreams come true in ways he never expected?
When Hiroya Matsumoto joined the Right Trading Company, he never thought he'd be anything more than a regular employee. But as it goes, he became the fifth member of a superhero team called the Shinesman. The Shinesman's mission is to defend the Earth against enemies from the Planet Voice. But amidst all this, Hiroya also has to look after his little brother, make a living, and do his superhero jobs clad in lame suits and equipped with equally lame weapons such as business cards! Can the Shinesman succeed in the face of utter comedy... I mean... terror?!
Cyborg 009 Conclusion - God's War is intended to be a proper conclusion to the original Cyborg 009 series.
Z is the son of a scientist killed in a duel with another scientist. He is trying to right the wrongs of his father, but will people let him do it?
Ten years ago, artificial biological implants known as "augmentation parts" were introduced into society. At the time, no one suspected the sinister turn of events that would come about because of body augmentations. And as the politicians and police stood by, the world watched as cyborg criminals, otherwise known as "augs," turned the world on its head...
Okamine Mikie idolizes her superior AST member, Tobiichi Origami, and may be in love with her as well. Unfortunately, Origami seems to want nothing to do with her. One day, they end up heading toward an explosion that wasn't caused by a spirit. Instead, it was caused by a girl named Ashley Sinclair, who transfers to their school shortly after the incident!