Train Heartnet was once a legendary assassin known as "Black Cat" and belonged to a secret society called Chronos. But two years ago he faked his own death in order to leave Chronos and become a bounty hunter, able to live by his own rules. His main mission in life now is to find Creed Diskense, a former Chronos member who killed his best friend. Train and his partner Sven are joined by a sexy thief named Rinslet and an amazing young girl named Eve who is a creation of nanotechnology!