Shushibaruba

Shushibaruba is an ancient monster that was awakened by Simon. It is the final boss of One Piece: Great Hidden Treasure of the Nanatsu Islands.

Appearance
In its dormant form, Shushibaruba is a translucent sphere resembling frogspawn.

In its first awakened form, it has a roundish shape with gold and purple colors, resembling a robot or machine. It has three arms, with one extending from the middle of its torso.

In its "true form", Shushibaruba possesses octopus or squid-like tentacles and a second mouth on its torso.

Personality
Shushibaruba does not exhibit much a personality, but Simon described it as completely rejecting Devil Fruit abilities. Shushibaruba seemingly devours any Devil Fruit users it comes across and causes destruction if let out of control.

During the final phase of its battle with the Straw Hat Pirates, Shushibaruba appears to possess some remnants of Simon's consciousness and echos his ambitions.

Abilities and Powers
Shushibaruba's potential power is immense, as it was capable of destroying entire islands and terraforming them, causing the creation of the Nanatsu Islands. Simon believed that with the power of Shushibaruba under his control, he would be able to take over the world. The Straw Hat Pirates and the Laotour Bandits agreed that the Marines or pirates would not stand a chance a chance against Simon if he could control Shushibaruba. However, in order to reach its peak, Shushibaruba must undergo growth by devouring multiple Devil Fruit users. When Shushibaruba becomes dormant, it reverts to an egg-like state and can only awaken by eating a Devil Fruit user. Even if it is awakened, it cannot achieve its maximum power with a single Devil Fruit user and could still be defeated by the Straw Hat Pirates.

In its first awakened form, Shushibaruba's arms have the ability to nullify Devil Fruit powers, such as Luffy's rubber powers or Chopper's transformations. However, if the arms are destroyed, the nullifying effect disappears. In this form, it is also capable of turning its arms into spikes to stab its opponents. In its true form, Shushibaruba becomes massive and is able to use its spiked tentacles to stab faraway opponets. Its only weak point in this form is its head. Shushibaruba can also take a humanoid resembling someone it has devoured, as seen when it transforms into a Simon-like form. In this form, it is capable of creating up to two duplicates of itself, and breathing fire, ice or lightning.

Past
Shushibaruba was originally created by an ancient civilization. In the past, its power caused an island to split into seven, creating the Nanatsu Islands. At some point, Shushibaruba became dormant on Na Island, reverting into an egg-like form. The ancient civilization then hid Na Island in the clouds, and made it so that it could only be summoned by using six treasures, which were hidden across the six remaining islands.

Great Hidden Treasure of the Nanatsu Islands
In order to awaken Shushibaruba, Simon summons Na Island using the six treasures and enters the Ku Sivan temple where it lays dormant. The Straw Hat Pirates, Ko and Simon eventually reached the Nu Sivan Kuru chamber where the Shushibaruba egg was hovering above a pedestal. Simon planned to use Luffy and Chopper as bait awaken Shushibaruba, but he was defeated by the Straw Hats before he could do so. Simon then made contact with the Shushibaruba egg, believing he could somehow become Shushibaruba himself. However, Shushibaruba merely devoured Simon and grew into its awakened form.

While the Straw Hat Pirates were shocked by Shushibaruba's appearance, Ko reassured them that it could still be defeated at this stage. However, Shushibaruba used its arms to nullify the Luffy and Chopper's Devil Fruit users. Hei then appeared with two of his subordinates and destroyed Shushibaruba's middle arm, before being defeated by the monster. Hei told the Straw Hats that the arms were the key to its Devil Fruit nullifying power, with this information Zoro and Sanji focused their efforts on destroying them. After a while, they managed to destroy the arms, removing the nullifying effect and allowing Luffy and Chopper to fight in full capacity. Shushibaruba then transformed into its true from and continued the battle with the crew. Eventually, they managed to damage Shushibaruba to the point where it switched to a humanoid, Simon-like form. In the end, Shushibaruba was defeated by the Straw Hat Pirates, but its ultimate fate was unclear.