Fake Chainsaw Man

Chainsaw Man's Doppelgänger (name unknown) is a mysterious figure which appears multiple times throughout the story. His goals and affiliations are currently unknown much like his true identity.

Appearance
He appears to be an exceptionally tall male and has a rather bulky physique. His face was never shown and as such the details of his apperance currently remain unknown. In his transformed state, large chainsaws emerge from his forehead and arms; much longer than Denji's. Additionally as seen in the shadow, his face is also morphed into a demonic, mechanical shape with long, jagged fangs, similar to that of Denji's or Pochita's devilish forms.

Personality
Not much is known about his personality except that he speaks in a formal, polite, and calm manner. His actions so far hint at him wanting to help the real Chainsaw Man however he can. It has yet to be shown why he beheaded Yuko despite her feeling remorse for her actions and not posing an active threat. He also seems very knowledgeable about the Devils in Hell.

Justice Devil arc
After Yuko says her goodbyes to Asa, she sets of an a journey to find her Devil Hunter relative, seeking to find a way to return to a human form. She tried to get some rest on the rooftop of one of the buildings. He takes the opportunity to behead her in her sleep, presumably killing her.

Current arc
As the Falling Devil blocks the way for Denji's and Asa's escape out of Hell, he appears behind her, tearing her apart and incapacitating her. He explains to Denji that the Falling Devil does not tolerate customers who don't finish their food, and as a result, the rest of the devils in Hell will desperately try to devour Asa in order to satisfy her demands. He then asks Chainsaw Man to evade the other devils until sunrise.

Abilities
In general, he seems to be very powerful, as he has no qualms facing a member of the Primal Fears. Not much is known about the nature his abilities, however they are likely similar to those of Denji's hybrid powers. These abilities include:

Supernatural Powers

 * Chainsaw Manifestation: As part of his transformation he grows fully-functional chainsaws from his arms and head. These chainsaws are extremely effective at cutting Devils' flesh as seen in when he ambushed the Falling Devil. It is unknown whether he can extend chainsaws from his legs like Denji can.
 * Just like Denji he can also temporarily retract his chainsaws if he needs to do certain tasks, such as picking something up.

Physical Prowess

 * Enhanced Strength: He is shown to easily hold up Yuko's entire body with just one hand. Later after he incapacitated the Falling Devil he lifts her up as well, holding up her entire body weight with just his neck.