Thirty eight years ago, when the God Valley Incident took place at God Valley, Big Mom gave this devil fruit to Kaido, as they were crewmates and belonged to the Rock Pirates. Big Mom gave this devil fruit to Kaido and calls it a debt that Kaido can't escape.

Years after this incident, when Kaido was under Marine captivity, Vegapunk extracted some lineage factor and created the Artificial Devil Fruit. This artificial devil fruit was eaten by Kozuki Momonosuke, thus Momonosuke could transform into a Dragon like Kaido, but Momonosuke still needs to have a good grip on his powers.

The Uo Uo no Mi, Model: Seiryu is spherical and a bit oblong in shape, it resembles a pinecone in some ways. It has a blue exterior with scales on it. Each of these scales has a small, dark-blue oval in the middle that has the devil fruit Spiral at the bottom. The scales on the outer portions are of a light blue shade. The fruit has orange leaves and two identical but separate stems with one being purple and the other a light pink color.

As it is a Zoan-type Devil Fruit, it boosts the user's physical strength by a large scale. When the user transforms into a full Dragon form, they can easily destroy buildings just by flying by them. Even though the user's arms are thinner than the rest of the Dragon's body, they are still very strong as they can rip apart houses and rocks quite easily. Apart from their raw strength, the user's size also plays a role in their mobility as they can move with great speed while keeping pace with fast enemies too.

The scales that cover the user's Dragon body are extremely durable. It cannot be penetrated easily and acts as a strong defense for the user. Other than the transformations, the fruit also grants multiple supernatural abilities. One of them is to be able to make Flame Clouds, with which the user can travel through the air by using them as footholds. These clouds can be used to lift up objects and islands in the air and move them. While doing this, the user can also use different power simultaneously. The user doesn't need to transform in order to use Flame Clouds.

The user can create and control various elements when they are in their hybrid or full form. They can use fire in a concentrated scorching blast of fire that the user breathes out which can travel large distances in seconds. The user can also launch lightning bolts too.

When the user is in their hybrid form, they can see their Dragon strength that runs through their body. This grants them a boost in agility and speed and helps them in combat. The user can also access their elemental attacks too.

Even though this devil fruit is very powerful, it does have some weaknesses. Due to the huge space the user takes up after entering their full form, they are only able to move in an enclosed space, which causes problems. The user's body is so massive that it is quite open to attacks and it makes them an easy target. Even though the Dragon's scales are durable, they are still weak against attacks that can pass through them, like attacks infused with Busoshoku or Haoshoku Haki. Their ability to breathe fire can be countered by anyone who can cut flames. If the user loses consciousness while using Flame Cloud, then it will disappear. Other than that, they have the standard devil fruit weakness, that is the inability to swim.

Kaido uses his devil fruit power for combat. He usually starts his battles in his full Dragon form and then transforms to his human form when he gets more serious and so that he can engage in one to one combat. If his enemy can handle both his forms, then he transforms into his Human-Beast Form, which is his strongest form. He goes all out on his enemies when he is in this form and it greatly enhances his abilities.

When Kaido is in his full Dragon form, he hovers a bit far away from enemies so that he can attack them with a long range àttack. When he enters his Human Beast Form, Kaido wields his kanabo. With the amount of boost in energy he has, he swings the club with extreme force which causes major shockwaves and striking melee blows which can injure anyone severely who comes in contact with it. Kaido is very fast in his Dragon form and can move slithering through the air by using his Dragon tail to propel himself forward or upwards. His tail is also able to capture his enemies off guard.

When Kaido drinks alcohol, he enters into a state known as Shuron Hakke which allows his movements to become unpredictable and makes his haki stronger. This state has various modes depending on his drunken mood swings like Warai Jogo, Ochikomi Jogo, Nami Jogo, Osorio Jogo, Amazon Jogo, Nusubito Jogo and Satsuriku Jogo. Kaido can create Flame Clouds and uses it primarily as foothills or to levitate himself in order to fly or to travel easily between islands. He can also levitate objects and whatever he wishes to float away.

The techniques used by Kaido are:

Bolo Breath

This technique is Kaido's signature move. In this technique, Kaido gathers fire inside his mouth before breathing it out in a huge, conical blast towards his target. This blast travels rapidly and is really powerful.

Kaifu

In this technique, Kaido blows with a strong force which creates a powerful crescent wind blade that can easily cut through solid stone as well as humans.

Tatsumaki

In this technique, Kaido spins his serpentine body into a coil to summon several tornadoes around him. As these tornadoes are quite strong, they are able to pull people away from the ground.

Kaen Daiko

In this technique, Kaido breathes a large amount of flames from his mouth which form a giant fire Dragon over his original Dragon form. This fire immediately melts anything that it touches.

Q. What does Uo mean?

A. Uo in Japanese translates to fish.

Q. Why does the fruit’s name translate to fish?

A. The fruit's "fish" designation is a reference to the connections present between dragons and fish in East Asian (especially Chinese) mythology. The story says that if a carp successfully swims upstream and make the jump, it is transformed into a majestic dragon.