The Dullahan, also known as Gan Ceann ("without a head"), is a type of mythological creature in Irish folklore. He is depicted as a headless rider, on a black horse, who carries his own head held high in his hand.
—Item description, Persona Q: Shadow of the Labyrinth
The Dullahan is a weapon for Kanji. It can be purchased from the Handcrafted Workshop for ¥65,000 after selling eight Bull Pieces, dropped by Minotaur I in the Clock Tower.