Black Cat (manga)

Black Cat is a manga written by Kentaro Yabuki.

 This is about a man named "Train" who withdraws from an organization called "Toki-no-bannin."  This organization was formed to wipe out evildoers.  There are thirteen people who do this job.  Each of them owns a weapon made out of special steel called "Oriharukon. "  Train was the thirteenth one who owned a gun made out of this Oriharukon.  He appears like a cat, and disappears like a cat, and never failed any jobs.  Any evildoer who meets him gets killed.  This is the origin of nickname "Black cat," the thirteenth, an ominous man who delivers death.  The reason he left the organization was because of the influence that a woman named " Saya Minatsuki."  Train never had any emotions towards doing his jobs. He had never laughed before, and even gets angry.  He was always expressionless. By meeting Saya, he had become to have emotions.
 Unfortunately, Train's comrade, "Credo" starts to feel hate towards Saya because she is the one who is changing Black Cat into just a normal man.  So when Train was gone, he kills Saya.  Train gets mad at Credo and tries to vengeance for Saya.
 He travels around the world with his partner "Sven." On the way, they make a new fellow named "Eve."  They are still on their way and the story goes on.