One of the most criticized points of Kimetsu no Yaiba is that its plot is too simple.
The original manga and anime have never focused on world settings, most of the rules and world of Kimetsu no Yaiba are introduced from the beginning and do not seem to change until the moment the story ends.
From the beginning, Kimetsu no Yaiba orients viewers and readers about its purpose and ending, when Giyu Tomioka tells Tanjiro that the only chance to turn Nezuko back into a human is for him to join the Assassins.
All the information regarding the world setting is wrapped up in the Tanjiro training arc and after this arc ends, the characters don’t mention it again.
For example, in the second chapter of the manga or anime volume 2, fears about demons and their existence are not even mentioned.
The content of killing demons to find a cure is not something new, but when used in Kimetsu no Yaiba, it does not create a boring feeling for viewers thanks to the unique characters.
To keep the demon slaying missions interesting, Tanjiro’s group is accompanied by different pillars in turn.
Kimetsu no Yaiba has a very clever strategy of focusing on each character in each arc instead of allocating time spread out.
Another strong point in Kimetsu no Yaiba is the maximum exploitation of humorous situations, helping the audience have a deeper look at the character, even when that character is not funny.
This is something that will be very difficult to achieve if you create a plot that is too complicated.