Murasame and Masamune were swordsmiths in early Japanese history, in a rivalry test of their swords they were placed into the slow flow of a river with sakura leaves running the surface. Murasame's blade cut the leaves as they softly passed while the leaves avoided Masamune's blade. Because of these events, whether they are true or only legend, Murasame's blades were considered to be dark blades and Masamune's were considered to be holy blades. Masamune is considered the greatest swordsmith of all time and his name has basically become synonymous with "incredibly well made sword"

In Final Fantasy VII, Sephiroth uses Masamune which is an unrealistically long thin blade that he wields with ease. Cloud can find the Murasame and use it himself, and it is a version of the Masamune that is about half the size. It is the thinnest blade that Cloud can use in the context of the game.