Future Devil

"The future is best!"

The Future Devil (の) is a devil that embodies the fear of the future. After seeing Aki Hayakawa's future, it made a contract with him, so he can see that future himself.

Appearance
The Future Devil's lower half resembles a tree growing from the floor with branches and a trunk extending up to a humanoid body with outstretched arms and a horned head. Multiple vine-like streamers grows from its arms and chest.

Its face has three pairs of eyes stacked on top of each other vertically and its wide mouth is almost perpetually open.

The Future Devil has a large hole in the center of its chest, inside of which is another oversized eye.

Personality
It has a extremely playful personality, regularly boasting that the future is best. The Future Devil's contracts are typically very costly, but after witnessing Aki's future, it gives him a contract on the condition that it be allowed to reside inside his eye to witness his horrible future up close, mocking him.

After showing Aki a vision of the future, he questions the devil on its motive, only for it to respond that he must shout "The future rules!" before summoning it, which Aki quickly rebuffs.

Different than other devils, Future Devil will not just wait until he is called and sometimes intercepts the hunter's life. He gives Aki the future about his death, making Aki desperately tries to find a way to save both Power and Denji which results in himself killed by Denji solely.

History
At some point the Future Devil was captured alive by Public Safety and locked up. It went on to make contracts with two Public Safety Devil Hunters, with one of them giving up half their lifespan and the other giving up both eyes, their sense of taste and their sense of smell.

Katana Man arc
Kurose and Tendo lead Aki to a place where devils are locked up by public safety in order to find him a new weapon. They lead him to the Future Devil and tell him to make a contract with it. Aki enters the Future Devil's room and sees its full appearance as it announces repeatedly that the "future rules".

Aki and the Future Devil talk, and the Future Devil disapproves of his attitude. It orders Aki to stick his head in its belly so that it can see his future and uses that to determine the details of their contract. After laughing at Aki's future, the Future Devil makes the offer that so long as it can live in Aki's right eye, it will help him. It reveals that the reason for why this contract is cheap is because it wishes to see Aki's future with its own eyes and that Aki is fated to die in "the worst way possible".

Gun Devil arc
Upon Aki's death at Denji's hand, the Future Devil reappears, laughing. He comments that he "died in the worst way possible... for the Chainsaw Boy," revealing that his death was meant to be horrible for Denji and not Aki himself.

Abilities
As a Devil, the Future Devil possesses all of the standard devil abilities, such the ability to make contracts with humans for a price. It's implied that the Future Devil is fairly strong, as Kurose and Tendo take Aki to see it in order to find a weapon he can use against Devils after the Fox Devil ended their contract.

The contracts with it seen so far are: Presumably, most contracts with it give the Devil Hunter the ability to see the future momentarily. However, as Aki discovered in his fight with the Ghost Devil, there is a notable weakness in that being able to see the future does not guarantee that you can act on it, as he was overwhelmed by the Ghost Devil's barrage of attacks despite being able to see them coming.
 * A contract with Aki Hayakawa, in exchange for letting the Future Devil reside in his right eye, Aki can see 4-5 seconds into the future.
 * A contract with an unnamed Public Safety Devil hunter, in exchange for half their lifespan, the Devil Hunter can use the Future Devil's power.
 * A contract with an unnamed Public Safety Devil hunter, in exchange for their eyes, sense of taste and smell, the Devil Hunter can use the Future Devil's power.

Devil Powers

 * Future Sight: By having someone insert their head into the hole in its chest, the Future Devil can see that person's future. It may also impart these visions on its contractors of its own volition, which it is only seen doing to cause distress about the future. This allows the hunters to change their own future, for example: Denji is supposed to slaughter both Aki and Power, but since Aki makes a contract with Makima after the sight, Denji only kills Aki.