One Piece chapter 1167 has been released, and it seems Oda has dropped the first major clue about the type of Devil Fruit Imu might possess. From the hints revealed, Imu’s power is connected to the Sea Devil, and he may actually be that entity.
One Piece 1167 Teases Imu’s Sea Devil Power

Chapter 1167 focuses on King Harald and his induction into the Holy Knights. With his incredible strength, he was granted a seal by the Five Elders. This seal is what grants great power to both the Holy Knights and the Five Elders. Naturally, this seal comes from Imu, as fans know he is the one who bestows various powers.
Although the full extent of the seal’s power hasn’t been revealed, it’s clear that the naming of these seals is inspired by the ocean. In other words, Imu’s ability is linked to the deep sea. Each seal is named after a specific ocean depth: the deeper the sea, the greater the power granted by Imu. Since fans already know Imu is a Devil Fruit user, this strongly suggests his power is that of the Sea Devil.
Imu’s Seal Has Three Ocean Depth Levels

While the full power of Imu’s seal remains a mystery, fans have identified three different depth levels:
Shallow Sea Seal: This is the most basic seal given to anyone by Imu and the Five Elders. It’s the seal granted to Shanks and Harald, as seen in chapter 1167.
Deep Sea Seal: This seal is deeper than the Shallow Sea Seal and grants more dangerous powers, such as immortality or even Devil Fruit abilities. High-ranking Holy Knights and possibly some of the Five Elders likely possess this level.
Abyssal Seal: The strongest form of the seal, representing the greatest depth, called the Abyssal Seal. Its exact abilities are unknown, but it’s assumed that the power of the Five Elders or even Imu himself comes from this level.
Imu’s Sea Devil Power Linked to the Earth God

At this point, it’s almost certain that Imu is the Sea Devil. His power comes from the ocean’s depths, which may also mean the sea does not affect him, making him the only character in One Piece to use a Devil Fruit without sinking underwater. This connection is emphasized by Imu’s use of the Abyssal Seal. To activate Domi Reversi, the target must sink into the Abyss, where they become enslaved.
Although Imu is the Sea Devil, this should not be confused with the Sea God of the One Piece world. The Sea God has been confirmed as Poseidon, whose power belongs to Shirahoshi. Therefore, Imu would be the Earth God, meaning he holds dominion over all natural elements, including the ocean, which makes him the Sea Devil.