Zetman by Masakazu Katsura
Summary from Wikipedia:
The story starts off with a face-off between two rival heroes, ZET and Alphas, and then traces their origins - Jin Kanzaki, a young man born/created with the ability to transform into a superhuman being known as ZET, and Kouga Amagi, a young man with a strong sense of justice who uses technology to fight as Alphas.
The fates of these two men and those around them intertwine as they fight to protect mankind and destroy monstrous abominations known as Players, who ironically are the creations of the Amagi Corporation, the company founded by Kouga's grandfather, Mitsugai Amagi.
I read the first few parts to this manga and wasn't able to put it down! It's awesome. Does anyone know if anything has been published past issue 80? I think Jin is one of my new heroes (he does get the ladies old or young).