After the flashback ends, all eyes turn to Imu, the main antagonist of One Piece. Oda not only hints at this character’s overwhelming power but also confirms that Imu possesses godlike abilities, directly connected to demons and evil. It is highly likely that Imu’s Devil Fruit is the Leviathan.
Imu Is the Demon God of One Piece

Few One Piece fans expected Imu to appear and fight so early, especially in the Elbaf arc. Oda truly shocked readers by revealing Imu, ready to confront Luffy right at the start of the Great War.
What makes the upcoming battle so compelling is that it will be a clash between gods. Just as Luffy is the Sun God Nika, Imu also wields divine power, most likely through a Devil Fruit.
Imu declared this upon arriving at Elbaf: “Let Me show you the dominion of a god!”
This at least confirms that Imu has godlike strength.
Imu’s Devil Fruit Is the Embodiment of Evil

While Sanji uses the power of Love (family power), it seems Imu can harness the power of evil. In other words, Imu’s Devil Fruit ability is directly linked to demons and darkness.
This explains why Imu can turn others into demonic puppets and even make them stronger. Imu told Brogy clearly: “I will grant you the power of demons!”
This power boost comes from the essence of evil itself, reinforcing the idea that Imu is the embodiment of the Devil (the Evil God).
Imu May Possess the Leviathan Devil Fruit

Imu’s design clearly shows a demonic nature. With black wings, a pointed tail, and a trident, this could be Imu’s true form or at least a manifestation of their power.
Putting these clues together, the best guess is that Imu wields the Leviathan Devil Fruit. Leviathan is a demonic sea serpent from mythology.
Its mouth is described as an Abyss, similar to the mark Imu uses. Leviathan can grant and take souls, much like Imu, who can bestow immortality and steal part of a lifespan or even a soul.
If Oda has revealed Imu’s power, it is likely the Leviathan ability, the ultimate embodiment of evil.