Jaryūki was a legendary five headed serpent-like beast that lived in the Underworld. The beast could spit powerful acid.
It was believed to exist in Hokkaido during the Meiji period. Gaō, his pack and the original hakkenshi of Sirius fought and managed to defeat it. As a symbol of their victory, the wolves ate the dragon's body. It's believed that Jaryūki's meat gave the wolves strange powers, explaining their Battōgas and other unusual abilities.
- Many fans believe Jaryūki is some sort of a dragon but it's never said to be one. It's only called a serpent monster. However, it's name does hint that it could be one by the meaning.
- Meteor Gin strongly hints that Jaryūki and the story of it might be just a made-up one.