The Chainsaw season 1 finale ruined a major comic moment
The Chainsaw anime was a great adaptation overall, but in their rush to please fans of the comics, they ruined a great future moment.

Warning! Contains MAJOR SPOILERS for Chainsaw Man's manga and anime!
The first season of the hit anime Chainsaw is finally over, and while the ending was generally great, the character teases at the end ruined what was to come in the comics. Part of what makes Saw so great is the amount of unpredictability that series creator Tatsuki Fujimoto has injected into every aspect of the story. After all, this manga is a major subversion of typical shonen series like Naruto. The final episode of Chainsaw Man's first season ended with the introduction of one of the most unpredictable characters, Reze.
After recounting the events of the manga up to Chapter 38, Saw Man introduces an anime-original tease of Reze, the central character in Saw Man's bomb demon arc. The anime doesn't reveal much about her, initially focusing on what's important to her character, then showing off her shoes and her hair, accompanied by the question of whether Denji thinks he's more of a country mouse or a city mouse. It's all very exciting for fans of the comics who've been waiting to see her adapted for the screen, and it's almost certainly confirmed that The anime will continue moving forward, but it ends up taking a toll on Reze's best moments in the manga.
Reze is a fan-favorite character, partly because her relationship with Denji seems to develop so organically. They initially seem to meet by chance, both sheltering from a storm, so their relationship appears to be a casual flirtation that develops naturally as they learn more about each other. It made things even more damaging when Saw's Reze revealed that their entire relationship was a ruse to get her close to Denji and steal his heart. This moment also kicks off the climactic battle of the Bomb Demon arc, leaving Denji and the reader with no time to process this startling betrayal before falling into chaotic action. However, Reze's teasing in the animation undercuts the shock of this great moment.
Reze Should Have Been Kept as a Surprise

Anyone who has only watched the anime now knows that Reze is an important character, and her relationship with Denji is not a surprise, but more like destiny. This would undercut the final reveal that Reze is an enemy demon hybrid, as the anime has made it clear that she's more than just a normal person girl. Worse, if the anime watcher chooses to interpret her lines in the ending as a sign that she already knows who Denji is, then it makes it seem like she doesn't know anything about him when they first meet, which could easily be dismissed Seeing through is a deception.
If the first season of Saw Man is anything to go by, Mappa may have done a good job adapting the Bomb Demon arc, despite the initial missteps. It's pretty cool to be able to now match the voice to Reze's character from the comics. But unfortunately, in order to provide manga fans with this immediate gratification, Chainsaw Man undercuts the impact of one of the series' best moments for those who only watch the anime.
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