Black Cat (Burakku Kyatto) is a manga series, or comic book series, that was created by Kentaro Yabuki, and is the series that he is best known for. The series was created and first released in Weekly Shōnen Jump in the year 2000. It was turned into an anime and was released in the United States in 2005. The manga ended at twenty volumes, and is just starting to be released in the United States.
Train Heartnet used to be a member of a group of assassins known as the Chronos Numbers. The Chronos Numbers were created in order to prevent an organization known as Chronos, which rules almost one third of the world. They created twelve special weapons, for twelve Chrono Numbers. Each assassin was marked with a number, as was their weapon. Train Heartnet was allowed to join because nothing that he aimed at remained alive for long. He became known as the Black Cat. Due to his joining, Chronos invented the number XIII for their Chronos Numbers. No doubt about it, Heartnet was the best. One mission, though, he was asked to assassinate a target, and the target’s child was there. Heartnet could not do it, due to his own childhood trauma.
He ends up meeting Saya Minatsuki, who is a sweeper, or a bounty hunter. He changed after meeting her, deciding to quit Chronos in order to become a bounty hunter himself. Creed Diskenth, one of Heartnet’s admirers, decides that it is Saya’s fault that Heartnet quit Chronos, and he decides that is whom he will take his anger out on. Heartnet gets to Saya too late, and is unable to defeat Creed, as he slinks away.