Location: Quibble Coinbiter's Seventh Shop - Battleon
Price: 6,000 Gold
Sellback: 1,500 Gold
Rarity: Unknown Rarity
Description: As the name suggests, this helm was once worn by the Imperial Guards on Yokai Island. No one will ever question your authority ever again.
Note: Also see Prismatic Imperial Guard Helm.
Thanks to LiteSage.