If his chainsaw cord is pulled while he has enough blood for the transformation, then his head will morph into a demonic, mechanical shape with long, jagged fangs and a chainsaw handle on the back. Large chainsaws will emerge from his forehead, arms and legs, he is able to retract and extract any of them at will.
Chainsaw protrusions: In his Hybrid form, Denji is equipped with chainsaws that come out of both of his arms, which he can use to attack enemies. He's also able to retract them at will and can generate them from other parts of his body, such as his legs.
Yes, Denji does have the ability to return to his human form. However only when he remains his conscious self. The only instance when Denji loses control is when he unlocks the true form of the "Chainsaw Devil" and begins to decimate his enemies whilst forcefully taking Kobeni out on a date.
Hybrid Form
Large chainsaws will emerge from his forehead, arms and legs, if he desires it. If Denji's chainsaw cord is pulled while he does not have enough blood, then a chainsaw blade will partially emerge from his face.
Darkness Devil
It has extreme speed and strength and can instantly dismember and kill multiple people. Making it the deadliest Devil. There are plenty of other deadly devils in the world of Chainsaw Man, but these are the ones I think make the cut.
But the war devil is much weaker than the control devil, at least, for now. During her last encounter with Pochita, the war devil lost parts of her body, which weakened her and the concept of war. If she somehow gains full control over the lost pieces, this devil can enrage wars in the human world.
Thus, Pochita, i.e., the Chainsaw Devil, can be considered the strongest devil in the series due to his exceptional ability to erase other devils' existence.
In the earlier part of the series, we notice that Denji is wearing an eye patch. This is because he sold his right eye, along with a kidney, and even a testicle, to gain some money to pay off his father's massive debts.
Power begins boasting about her high IQ, continuously lying and increasing its height. Suddenly, Himeno grabs Denji from behind, and kisses him deeply.
Immense Healing Factor: As a full Devil, Pochita's regenerative abilities are enhanced to the point that he completely regenerated his body from just his heart after throwing it from space without needing blood, even when suffering intense atmospheric entry burns.
Power. Power and Denji don't have a very romantic relationship, instead more so an awkward sibling relationship. While he finds Power attractive, it doesn't take long for the two to butt heads. Upon their first meeting, she makes a deal with Denji that if he's able to retrieve her cat, she'll let him feel her up.
So, why did this act come to pass? It turns out, Denji ate her in order to prevent her from regenerating, as Devils have the power to do so in spite of getting killed. Makima had always underestimated Denji and was obsessed with the Chainsaw devil within him.
Blood Consumption: Denji is able to heal completely from nearly any fatal injury, and in some instances recover from death, so long as he consumes a sufficient amount of blood. After losing his arm to Bat Devil, Denji's arm re-attached itself after he received a blood transfusion.
Power very clearly gives Denji exactly three fondles in recompense for saving her cat Meowy, not ratting her out to their boss, and killing the Bat Devil for her—all situations which worked wildly to her benefit.
Denji's main love interests in Part 1 of Chainsaw Man were Makima, Power, and Reze. While he did fondle Power's breasts, that was largely the extent of their romantic entanglement and Power became more of a sibling to him from that point onwards.
Power tells Denji that he gets three squeezes: one for saving Meowy, second for killing Bat Devil and third for protecting her from topknot. She reveals she wouldn't have allowed him to touch her, but changed her mind to repay him for his efforts.
In a deeply disturbing sequence, Himeno gets ready to go to bed, where she actively tries to seduce Denji and persuade him to have sex.
Later during his movie date with Asa, she tries to push him away presumably to keep him safe from Yoru. In response she takes over and kisses Denji likely in hopes of quickly winning his heart which would allow her to finally turn him into a weapon, but she is swiftly incapacitated by Nayuta instead.
Later, she asks him to take a bath with her, in order to keep her safe. The two shower, as Power continuously sobs about being attacked from behind. As the two get in the bath and lay together, Denji is surprised that despite the intimacy of their act, it doesn't feel sexual in any manner.
Ten years later, when the anime actually opens, Denji has already sold off several body parts to keep himself and Pochita going: an eye, a kidney, one of his testicles, and his only lamentation is that it did not earn more money! Take a moment and live with a world where a child sells body parts to survive.
Not only did Denji defeat Makima as himself, but he also eats Makima as himself. Remember, Makima stated at one point that if she was going to lose to Chainsaw Man, she wanted the honor of being eaten by him, the one she idolizes most. Denji is essentially denying her that dream by eating her as himself.
Unbeknownst to Asa and her possessor, The War Devil, Denji is, in fact, Chainsaw Man and the caretaker for the mysterious reincarnation of the Control Devil. Denji does his best to warn Asa of the dangers of visiting his home, but there may be more to worry about than the young girl under Denji's care.
As revealed in Chapter 87 of the manga, Pochita was in a battle with the four horsemen group of devils before reaching a near-death situation. In its weakened state, Pochita adopted a cute dog-like look and met Denji (protagonist).
Pochita's Violent and Infamous Past
However, it was during a battle between the Four Horsemen and the Weapon Devils, and was left badly injured and barely alive. This is when he became the small dog form we first see Pochita as.
Why does Pochita love Denji? A. Pochita loves Denji because he is the first human who has ever shown him kindness and affection. Denji saved his life, which created a strong bond between them.