Over the course of two decades, One Piece has become one of the most popular anime and manga franchises in history, thanks in part to Devil Fruit users. Logia fruits allow their user to control and transform into an element, while Zoan-types offer animal transformations. Paramecia fruits offer a wide range of powers that alter a person's body or surroundings.
Fans have seen dozens of Devil Fruits over the years, and some are incredibly powerful. There are a number of Devil Fruit powers that would be very useful if they existed in real life, but there are also quite a few that offer no practical use whatsoever.
10 The Jacket-Jacket Fruit Literally Turns Someone Into A Jacket
Kelly Funk is an assassin who ate the Jacket-Jacket Fruit, a Paramecia which allows him to transform into a full body jacket. The user can be worn by humans and animals, and they can control the wearer's body and utilize their physical strength and speed.
It's hard to believe that anyone in real life would go out of their way to become someone's jacket. This fruit requires someone to actually wear the user, otherwise it is completely powerless, making it one of the worst Devil Fruits in One Piece.
9 The Kilo-Kilo Fruit Makes Someone Lighter Or Heavier Without Any Physical Changes
Miss Valentine was an agent within Crocodile's Baroque Works organization, and she ate the Kilo-Kilo Fruit. With this fruit, she is able to change her weight, but the power is limited. At minimum, she can weigh just 2 pounds, while her maximum weight is set at 22,000 pounds.
Normally, a power that allows someone to lose weight would be highly coveted in real life, but this fruit does not change the user's physical body, which means that they do not receive any health benefits from the weight loss. It basically makes the idea of weight loss pointless.
8 The Ripe-Ripe Fruit Makes People Age
Minor issues aside, the Wano Arc has been fantastic and has introduced a number of Devil Fruits, including Shinobu's Ripe-Ripe Fruit. This Paramecia allows its user to cause anything that they touch to mature or decay.
This power works on people too, but their mental state remains the same, and the target cannot return to their original age. This means that someone can give a 30-year-old body to a toddler who can barely walk and cannot speak. Most people would prefer to stop aging because of sickness, frailty, and death, so a power that accelerates aging would be counterintuitive.
7 The Mark-Mark Fruit Is Only Good For Sniping & It Barely Even Helps
The Mark-Mark Fruit is a Paramecia that was eaten by the evil Vander Decken IX, and it gives him the ability to aim at a target from any location at any time. This is the type of Devil Fruit power that real life snipers would love, but in terms of actual functionality, it would barely help.
In order to mark the target, the user has to physically touch it with their hand. If the same hand touches something else, however, the initial target is negated. The object that's fired will hit its target, but the user can't control where it hits. Even worse, if anything gets in the way, the fired object will hit that object instead of its target.
6 The Swim-Swim Fruit Eliminates Actual Swimming
.jpg?q=50&fit=crop&w=750&dpr=1.5)
Senor Pink has a sad backstory, but his design is terrible, and his Devil Fruit is not all that impressive. The Swim-Swim Fruit allows him to swim through the ground. He can swim through walls too, and he can even defy gravity by swimming up walls.
The problem with this fruit is that it does not offer any type of advantage in regard to travel, and it requires the user to swim without increasing their endurance. The only reason a real life person would want this power is if they are bored with swimming in actual water, but doing so might eliminate actual swimming forever.
5 The Ton-Ton Just Makes Its User Heavier
Machvise was an officer with the Donquixote Pirates, and his Devil Fruit allowed him to make good use of his size. He ate the Ton-Ton Fruit, which gives him the ability to increase his weight to incredible levels. The weight can be increased by metric tons, and he used it to crush his opponents.
In a world where the majority of people want to lose weight or maintain a healthy weight, this Devil Fruit makes no sense. This is especially true since the added weight can be used against the user in certain scenarios.
4 The Rust-Rust Creates Rust, Which No One Wants
.jpg?q=50&fit=crop&w=750&dpr=1.5)
When the Straw Hats dealt with the Buster Call on Ennies Lobby, they were forced to fight a number of Marines, including Captain Shu. He ate the Rust-Rust Fruit, which gives its user the ability to rust and pull apart metallic weapons.
In real life, rust is a terrible thing. In fact most people either throw away a rusted object or fix it up. It's also the reason why people rust-proof their cars. Worse of all, this ability seems to activate automatically, so the user might accidentally rust something important by simply touching it.
3 The Berry-Berry Fruit Just Turn's The User's Body Into Orbs
The Ennies Lobby Buster call also introduced Captain Very Good, who ate the Berry-Berry Fruit. This Paramecia allows its user to separate their body into a bunch of berry-shaped parts that can float in midair. This power does absolutely nothing against skilled sword users, but it does nullify damage dealt by blunt attacks like punches.
When it comes to offensive potential, this fruit offers nothing, and its defensive capabilities are useless if someone grabs hold of the user's head. In the end, this fruit is only good in a fist fight, and since most people in real life try to ignore fights, the ability to become floating orbs is useless.
2 The Spring-Spring Fruit Lets The User Turn Their Limbs Into Springs
Bellamy retired from piracy after the Dressrosa arc, and he managed to accumulate a bounty of 195,000 berries despite having a silly Devil Fruit. He ate the Spring-Spring Fruit, which allowed him to turn his limbs into springs. The resulting compression allowed him to throw strong punches.
In terms of real world applications, the only real benefit that this Devil Fruit offers is the ability to jump pretty high at relatively fast speeds. It's by no means a safe method of transportation. Once a person jumps, they will travel in a straight line, and they won't be able to alter course if another person or object moves into their path.
1 The Human-Human Fruit Would Be Completely useless
Chopper is the doctor of the Straw Hat Pirates, and the only reason he has the position is because of his Devil Fruit. He ate the Human-Human Fruit, a Zoan which gives the user the ability to transform into a human or human hybrid. Without it, he would be an ordinary reindeer.
There is no reason for a real life person to feed this to their pet, because at that point, the animal will not be a pet anymore. If a human were to eat this fruit, it would have no effect besides making the user unable to swim, making it the definition of useless.