Zetman (ゼットマン, Zettoman) is a manga series by Masakazu Katsura. The series started as a one-shot in a series of four published in Weekly Shōnen Jump between 1989 and 1994, and collected into a tankōbon released in 1995. A more mature and full-fledged series started in Weekly Young Jump in 2002. Zetman has been adapted into an anime series that premiered on April 2, 2012.
The story starts off with a face-off between two rival heroes, ZET and Alphasz, and then traces their origins - Jin Kanzaki, a young man 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 Alphasz. 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.