I am Muramasa.

Where there are demons, I slay them.
Where there are saints, I slay them.

Good is not my nature. Justice is not my purpose.
The righteous path is not mine to walk.
Good and Evil alike shall perish beneath my blade.

I am a weapon, a tool of murder.
You who would call yourself my master, hast thou the resolve to become what I am?

If nay, then begone.
If yea—then stand forth, and speak the covenant.