Muramasa Sengo was a swordsmith in 16th century Japan. Though an excellent swordsmith, he was said to be insanely ill-tempered, verging on just straight-up insane. This trait led to myths that swords made by him were [[{{EvilWeapon}} cursed with the same afflictions]], encouraging the wielder to fight to the death, and would, if no battle was present, turn on their owners and [[{{DrivenToSuicide}} compel them to commit suicide.]] These rumors weren't helped by the fact that Shogun Tokugaya Ieyasu banned Muramasa blades because many of his friends had been killed by them, and that he had accidentally cut himself badly with one.

In fiction, Muramasa will usually be a rival of [[http://en.wikipedia.org/wiki/Masamune Masamune]] (Never mind the fact that [[{{Artistic license history}} they didn't live in the same time period]]) as well as AlwaysChaoticEvil.

His swords will usually be [[{{EmpathicWeapon}} Empathic]], [[{{Axcrazy}} bloodthirsty]] (Possibly even absorbing blood into the blade to strengthen itself, or [[OurVampiresAreDifferent encouraging the host to do so by cursing them.]]) and have an ObviouslyEvil appearance aura about it (Notches, rust, bloodstains, ect.) The blade may alo take near inhuman force of will to sheathe the blade once unsheathed until blood is drawn with it. In sharp contrast to the swords made by his rival, If a character reveals they use either of these, expect the Muramasa user to be evil, or at the very least, [[{{AntiHero}} morally grey]], and the Masamune user to be good ([[VideoGame/FinalFantasyVII most of the time]]).
----