Tatsuki Fujimoto's Chainsaw Man is a manga known for its bloodthirsty action scenes and over-the-top ultraviolence around every corner, but the series also has a very intricate network of lore. There are still a plethora of mysteries from Chainsaw Man’s Part One that have yet to be solved, but none perhaps as intriguing as this one…
The entire final portion of Chainsaw Man Part One revolves around the final battle with Makima and her devil cohort which have been bent to her will. It appears as though throughout the entire series, Makima was slowly collecting a group of humans that could transform into devils in order to do battle with Chainsaw Man. Among this group of humans that can transform into devils are Quanxi, the Crossbow Devil, Reze, the Bomb Devil, and the mob boss’ son who became Katana Devil. Additionally, there are other people who make their appearance for the first time, such as the Longsword Devil, Whip Devil, Flamethrower Devil, and Spear Devil.
The climactic Chapter 87 of Chainsaw Man is where Makima reveals the greatest mystery still unsolved in the series itself. She states that the humans that can transform into devils are not humans, devils, or fiends but something completely different altogether. She then adds that the name these hybrids once had was eaten by Chainsaw Man and erased, but the hybrids themselves still remain. As far as readers are aware, this is the only known case where something eaten by the Chainsaw Devil still exists in the corporeal physical world. Prior to this instance, it was established that every Devil consumed by Chainsaw Man would disappear forever and have their names forgotten by all humans and most devils as well. These hybrids are the only case where Chainsaw Man’s existence erasure power did not work completely and this could have huge implications for the series’ second part.
So far, Chainsaw Man has established the parameters for what most of its supernatural creatures are. Devils are creatures born in Hell that are given a name that correlates to an existing fear within the human population. Their strength is also associated with how many people fear their aspect and to what degree. A fiend is a being that is created when a Devil possesses a corpse- notable examples being Power, Quanxi’s girls, and Beam. Technically Asa Mitaka, Chainsaw Man Part Two’s protagonist would fall under the category of fiend but there’s something not quite right about her transformation. In every other case of a fiend, the possessing Devil has full control of the corpse and doesn’t typically need to activate some kind of transformation. In Asa’s case, however, she shares control with the War Devil and does physically transform when using its power, making her much more similar to the unnamed hybrids mentioned by Makima.
This mystery is extremely important because it brings up another unanswered question- what happens to the Devils eaten by Chainsaw Man? As far as readers know, they simply cease to exist or be remembered at all, even altering past events when they’re consumed. The reason for the continued existence of these devil-human hybrids could very well be one of the keys to a much larger plot at the heart of Chainsaw Man. As it stands, the question of why and how these hybrids still exist despite having their corresponding Devil consumed by Chainsaw Man is the most prevalent unsolved mystery in the series.