Origin: Japanese Mythology
Dragons Slain: Yamata-no-orochi
Susa-no-o, the Dragon Slayer
History: Susa-no-o, the storm god, was cast into the Yomi Land (Netherhell) when he managed to force his sister, the Sun Goddess, into seclusion with his mischievous ways.  His name means 'Swift-Impetuous-Deity'  or 'The Impetuous Male.' 
After descending from the heavens, he became well-respected, if not still mischievous. He spent his time in the Province of Izumo.  It is here that he laid eyes upon the terrifying eight-headed dragon Yamata-no-orochi. 
Susa-no-o arrived at the river Hi and heard the sound of weeping. He followed the sound and discovered a young woman and two elderly people, Ashi-nadzuchi, meaning 'Foot-Stroke-Elder,' and Te-nadzuchi, meaning 'Hand-Stroke-Elder.'  These were early deities weeping, so Susa-no-o inquired about their tears.
They explained that a monster would soon eat their daughter Kushi-nada-hime, meaning 'Wondrous-Inada-Princess.' They had eight daughters, and of all of them she was the last, the other seven fallen pray to the same monster. 
On the promise that Susa-no-o would marry Kushi-nada-hime, he promised to slay the serpent. He made his bride-to-be into a many-toothed comb and placed it in his hair for safe keeping. 
The hero took the bowls of sake and placed them in the path of the dragon. In some versions, the sake is poisoned.  The dragon, upon seeing the sake in his way, early drank it all, each head to its own bowl. Yamata-no-orochi became drunk and fell asleep. 
Susa-no-o, now with nothing to fear, took his ten-span sword and chopped the dragon into little bits.  In so doing, his sword became notched trying to chop up one of the dragon's tails. There he found a sword named Murakumo-no-Tsurugi,  now a part of the imperial regalia. 
- Susa-no-o is the storm god 
- The Earthly deities Ashi-nadzuchi and his wife Tenadzuchi suffered from the wrath of Yamata-no-orochi. 
- The only surviving daughter of Ashi-nadzuchi and Tenadzuchi was Kushi-nada-hime. 
- Susa-no-o tricked the dragon with sake. 
- Susa-no-o found the sword Murakumo-no-Tsurugi inside the tail of the dragon. 
For more information on footnotes and references, please see the bibliography.