A group of assasins are controled by Chronos. They all have a number on
their neck. But number 13 which is Black Cat has the characteristics of
a cat, because a witch cursed him. He is supposed to kill people but he
also hates the thought of killing people.
The world is secretly controlled by a secret organizition, Chronos.
Under the command of this mysterious organization, are the Chronos
Numbers, a group of powerful assasins, taking orders to eliminate
certain target secretly to keep the so-called 'peace'. One of the most
powerful is the Number XIII, Train Hartnett, or known as Black Cat. At
first he seems to be a cruel killer, a meeting with a girl Sweeper
changed him completely. Now as a Sweeper, Train travelled with his
partner Sven Volfied to hunt down criminals.
Train Heartnet is known as the Black Cat for his quick reactions to
attacks and his title as Number Thirteen as member of the secret
society Chronos. He is an unbeatable master gunman, a cold and
unfeeling killer until he meets Saya, a bounty hunter, or "sweeper".
She teaches him the value of a human life, and that one should live in
order to repent for one's mistakes rather than die because of them.
Through her, Train learns to love and care for other people as he too
becomes a sweeper and travels with his partner Sven and the mysterious
girl Eve.
