The Oni Oni no Mi, Model: Gashadokuro is a Mythical Zoan Devil Fruit currently consumed by Kairo. It enables the user to utilize the abilities of and transform into a Gashadokuro, also otherwise known as Odokuro for whatever purpose, making them a Humanoid Yokai. The Ronin discovered the fruit as a child in a fruit basket that his father had, who'd found the fruit amongst the mountains of Wano Country.
The fruit takes the appearance of a miniature melon similar to a watermelon. The outside of it along the hard part is sever curving patterns. The actually edible part is white and black seeds, when Kairo ate it as a mere child, a small glow from it attracted him.