Lagend told that Yamata no Orochi had been slayed by God of Wind & Sea (Susano). Some people believe that Jiro is actually Susano from previous incarnation. Jiro said he keeps on dreaming about the battle . Orochi told him in the dream that he have to draw Orochi's face on one of his rifle to make the dream dissapear. Jiro then draw Orochi's mother on his rifle because no one ♥♥♥♥♥♥♥ order Jiro what he have to do. Orochi annoyed by that and left along with the dream. There are no prove for that, story but looking from his nature and this rifle it might be true. ;