The Hayashi-Aki is a mystical construct of the Ninja Tribunal and as such was exclusively created for the 2003 animated series.
Description[]
The Hayashi-Aki was created by the Ninja Tribunal as a first lesson for the Acolytes. It is a Fire Demon, with the body of a dragon. It has two arms, a long, whip-like tail and its body is red and black. Its wings are made of fire, and a fire ruffle surrounds its head. The Hayashi-Aki has a pointed tongue and rows of sharp teeth.
The Hayashi-Aki first appears as columns of smoke which can smash through walls and doors. It envelopes its captives in balls of smoke, keeping them suspended in mid-air. Its physical form manifests as a dragon, and it can breathe fire, which it grabs between its hands and turns into a huge sword.
A whip-like tail is used by the Hayashi-Aki to destroy solid objects and spread fire. The Hayashi-Aki is very strong and when Adam McKay hits its chest with his mace and chain weapon, the huge, spiked metal ball merely bounces off.
Joi Reynard manages to catch its sword wrist with her rope dart, but the creature pulls her into its chest, which opens to reveal tentacles. It uses these tentacles to capture Tora as well.
The acolytes are unable to defeat the Hayashi-Aki, which gloats at their failure, and then flies off into the night sky. It ceased to exist when it was revealed that the Tribunal created a vision in everyone's mind, illustrating that perception is not always truth, and that the battle ahead will be fraught with unforeseen dangers...