The Zan Zan no Mi is a Paramecia-type Devil Fruit that grants the user the ability to slice through anything their body alone, making them a Cutting Human (切断人間, Setsudan Ningen). Zan, however, literally means "beheading", implying the fruit once had a use for grooming executioners. True to the name, many past users of the fruit have referred to themselves as Executioner Humans (刑吏人間, Keiri Ningen) instead. It was eaten by Tessa Rose.
The Zan Zan no Mi has been used by several individuals in the past, many with ties to the World Government in some form, serving as assassins. Each of these individuals were given the title of Executioner Humans (刑吏人間, Keiri Ningen) due to the fruit's cutting properties being used for beheading — which was how it was named in the first place. After the most recent wielder of the fruit, the late Captain Silverbeard Jones, died, the fruit respawned, and was eaten by a young pirate named Tessa Rose.
The Zan Zan no Mi allows the user to cut through anything using their body alone, and this is an ability that can be amplified and applied in numerous different methods. The user's body alone becomes ridiculously sharp, generating what would appear to be an invisible field from the skin alone that cuts anything that approaches the user. This, however, makes the fruit dangerous to use, as casual contact with humans can render them asunder within moments, surfaces become difficult to walk on without slicing them into ribbons — making pedestals impossible to stand on — and clothes shred on contact. These, however, are weaknesses for inexperienced users. The first trials of consuming the Zan Zan no Mi require the user to control this field, and minimize its effects to cause less harm or no harm entirely, to the world at large. And as the user learns to control this field, they can expand, contract, and shape its range entirely, allowing them to release the field from their own body in a wave of invisible energy that carries the same properties of slicing through any material.