Tanjirou’s instincts are unusually sharp, but this scene understandably confuses many. Why is it a bad idea to cut the ropes between the dreamers and dream invaders? Luckily, the manga version gives us the answer. So, without further ado, why didn’t Tanjirou cut the rope?
Tanjirou didn’t cut the rope because this would cause the dream invaders to stay asleep for all eternity. Tanjirou concluded this fairly subconsciously, likely due to smelling the rope was of demon origin and knowing demons are weak to his sword.
The Demon Slayer (Kimetsu no Yaiba) manga explained this detail easily in 2 panels. Why the anime and movie didn’t include them will likely stay a mystery forever. In any case, you can find them below:
Demons are weak to the Nichirin sword Demon Slayers use. Therefore, it does make sense that cutting the rope with these swords would have a more dramatic effect than using demon blood. Still, it’s awfully impressive that Tanjirou was able to subconsciously deduce this so quickly.
The Mugen Train Manga
The Mugen Train Manga takes place from chapters 54 to 66. Both the anime and the manga are honestly faithful representations of the source material. However, that doesn’t mean that it’s not worth having as a fan.
You can buy volumes 7 and 8 of the manga (which includes these chapters) on Amazon here or click here to get the entire (completed) series (affiliate links). If you want to have an overview of all significant differences between the movie, anime and manga, then you should make sure to read our Mugen Train article.