Warning: contains spoilers for the latest chapter of Chainsaw Man
Makima may have divulged the true power of Chainsaw Man near the end of the series' first part and why so many devils either fear or worship him. Though this ends up answering one of the series' biggest questions, it leaves a random comment that the Angel Devil mentions much earlier a complete mystery.
For the majority of the manga, Chainsaw Man portrays Makima as a powerful character who few in her own organization trust on account of her terrifying abilities. Even readers are led to believe from the start that she's manipulating Denji into believing she cares for him just so he will do anything she says. When she finally reveals her actual identity and purpose in chapter 84, causing Denji to adopt a disturbing coping mechanism to compensate, Makima also shares the true terrifying power of Chainsaw Man and why she has been grooming him throughout the series.
Most devils who are killed and sent to hell are able to return to the land of the living so long as there are those who remember their name. This directly correlates to the devils' ability to grow in power so long as mankind's fear of them increases. But the names of the devils that Chainsaw Man eats are erased and completely forgotten, hence why many fear or adore the devil enough to share a bromance with him. But this terrifying ability isn't just restricted to devils. Anything he devours shares the same fate.
Makima first divulges this terrifying news to Captain Kishibe of the Tokyo Special Division 4 at gunpoint. Makima is able to prove her point, but the truth is lost on Kishibe because of Chainsaw Man's power. The reader knows the truth, however, just because everyone in real life knows about them. Makima mentions a notorious group known as the Nazis to Kishibe, but he has no idea what she's talking about because he's never heard of them. It's because Chainsaw Man devoured them. Makima also implies that Chainsaw Man somehow devoured abstract things such as man's sixth sense and four states of beings that humans could achieve after their lives ended other than death. Makima reveals to Kishibe she wants to use Chainsaw Man to create a better world by ridding hunger, war, and death from existence.
While this might seem to be the most incredible unveiling of anything that could ever be revealed in the manga, there's still one major mystery that remains. Earlier on in chapter 53 of Chainsaw Man, the Angel Devil tells Aki the devil hunter the truth about where devils go when they die and how they come back. Strangely, Angel and every other devil don't remember anything of their time in hell except a sound they hear the moment before they return back to Earth: The roar of a chainsaw engine coming to life.
Why devils hear this sound has never been explained. Even though it's never been proven, readers can't help but come to the conclusion that Chainsaw Man is somehow involved just by the obvious implications of such an incredible statement. If it's true, one has to wonder how Chainsaw Man becoming Denji's heart has affected this crucial moment for devils since Denji isn't in hell carrying out this ambivalent albeit ostensibly important role. The fact that Denji does descend into hell when Makima first explains his true powers to Kishibe but readers don't get to witness what actually transpires there is interesting. Maybe witnessing what happened in hell would have revealed the truth. But, then again, why didn't readers find out when Denji and his friends are literally tossed into hell before? Hopefully, Chainsaw Man mangaka Tatsuki Fujimoto will divulge the truth later on when he resumes his series.