Oni Oni no Mi, Model: Sea Devil

The Oni Oni no mi, model sea devil is a mythical zoan that allows the user to become a sea devil, in the process gaining a number of devil fruit realted powers. It was eaten by the Kiri-Nodachi, the sword used by John Jango de triezieme.

The user gains controll of a form of "Dark Matter" which has reversive effects on devil fruit weaknesses in high enough concentration. However they also have standard devil fruit weaknesses.