Nika is the name of a mythical warrior that was once revered as the Sun God by slaves from ancient times. He was first mentioned by Who’s-Who, who heard about the legend from a prison guard during his imprisonment by the World Government. There is no record of whether this figure is a myth or existed in ancient times.
There exists a Mythical Zoan-type Devil Fruit called the Hito Hito no Mi, Model: Nika that allows the consumer to gain Nika’s traits and abilities. For unknown reasons, the World Government is extremely interested in this fruit and has even covered up its identity by renaming it to the “Gomu Gomu no Mi”, preventing other parties from garnering special interest to the fruit and seeking it out themselves, such that not even members of the Four Emperors and their respective crews seem to be aware. Currently, the fruit’s power is in the possession of Monkey D. Luffy.