Space Adventure Cobra is a popular Shounen Jump manga from the late 70s, early 80s.

Cobra is a notorious Space Pirate with a laser gun as his left arm. But, he was tired of being chased by the agency in space and decided to lead a regular life by changing his face & being wiped of his memory.

3 years later, he is a regular person leading a regular life.

===== In the United States, portions of the manga were published by Viz Media in 1990. The feature film was licensed by Tara for its release in American theaters and by Manga Entertainment in British theaters in 1995. Urban Vision and Discotek Media released it for home video market, while Madman Entertainment acquired it for the Australasian region's release. The anime series was licensed in the Northern American region by Nozomi Entertainment. http://www.comicvine.com/cobra/4050-23937/