In Japan, two 'magical' blades exist. These are Masamune and Murasame swords. If you put the two blades in a river with floating leaves, the Masamune blade would repel the leaves and let them flow safely down the stream, while the Murasame blade would attract and cut them up. The Murasame blade is supposedly cursed, but very powerful. It is so innately cold, that water disperses off it when drawn and exposed to air. This test symbolizes the two periods and how chaotic the Muromachi period was.

Mythology