Yorimasa was the only knight brave enough to stand guard at the emperor's bedchamber and fight the cloud monster.

The emperor was so plagued by the evil cloud that he was unable to sleep. Others tried, but fled in fright. Yorimasa, armed with bows, arrows, armor and a cap, entered, shot the monster and once it fell to the ground, pursued it with his sword, and killed it. The emperor had the skin saved with the rest of his treasure.

Yorimasa was given the "King of Lions" / Shishiwo sword and married Lady Ayame.

As with other Eastern Dragons, this one is also a composite of many other animals including: ape, tiger, bird, serpent and dragon.