Demon Slayer aka Kimetsu no Yaiba proves to be a highly-unique shonen anime involving a protagonist named Tanjirou Kamado that aims to cure his sister's, Nezuko, demonic self.
After returning from a nearby village to make money for his family, he sees them all lying on the ground in blood. However, Nezuko was the only one left alive out of all of them. As time passes while carrying her to look for help, she awakens as a demon and assaults him... but wasn't able to kill him as the real Nezuko was still within herself.
Later on a demon slayer named Giyuu Tomioka joins the scene and tries to take out Nezuko. But Tanjirou was able to get through his head to not kill her while proving his worth by almost killing him to defend her. So he let's Nezuko go and tells him to look for his master to be trained as a demon hunter like he is so as to find answers on how to cure his sister.
Demons in this anime are deadly ex humans that feast on people in order to fulfill their hunger and become stronger. And if their blood enters a human's blood system, then they too become demons and develop intense cravings for human flesh. It's like a disease that can spread to others if any are left alive.
All of this entails to representing crime that occurs day to day in this world that we live in. Rural areas are especially non-friendly areas to be in if one isn't too careful; especially during the nighttime.
Demons are shown to harm everyone around them; whether they commit murder or infect others with the demonic virus. They are just like crime that exists today where it too causes harm to communities by getting people killed out on the streets and creating victims.
The spread of the demonic virus especially correlates to how some would turn to crime in order to survive instead of living off of honest pay that may not provide enough.
Demon Slayer Opening
Demon Slayer Closing
Not all demons are the same as there are those that snatch young women, establish "turfs," and more. All of this entails to just like how there are various kinds of crime that exist today. We have sex traffickers that steal women as well as thugs that establish their own territories.
All demons could be labeled as "murderers" due to killing people, but with the different types that exist (especially those capable of using magic), they each have their own unique symbolism to represent themselves.
There are some demons that are led by a higher up to be part of "organized crime." And their leader is the original demon to ever arise named Muzan Kibutsuji.
He has been alive for a very long period of time and symbolizes as the head of a mafia that spreads crime throughout various areas. He holds the highest amount of authority as any head of a mafia would have; making other demons fear before him as they are to recognize themselves as being below him and to never back stab him.
Teoni
Swamp Demon
Muzan Kibutsuji
But what does this all mean for Nezuko? What symbolism does she carry for being a demon herself but managing to keep herself under controlled from harming anyone?
She represents as someone that can turn to crime even within a household that tries to live honestly. Despite all of the hard work Tanjirou has done to provide for his family, this concept for Nezuko very much applies.
Say there's a low income family living together and struggling to make do with what they have. One person from their family works very hard, but whatever he/she earns may not be enough to provide for his/her family.
In which case, someone within the household may resort to crime in order to provide for the family and be made better off.
Disclaimer: this is NOT me claiming that Nezuko committed anything bad as this is to be taken as symbolism rather than literal.
Depending on the type of crime that person would be involved with, consequences are bound to happen such as being part of a gang and having a rival gang come over to that person's home while family is present and killing them all.
Another type of crime to pull up is drug abuse as it applies to those that go through stress in a low-income family and resort to drugs to ease themselves. Nezuko so far hasn't devoured a single human; therefore symbolizing her as someone that resorted to taking drugs and wishes to overcome addictions.
In which case, Nezuko would be in the recovering process of not succumbing to her temptations of human flesh while his brother aims to get her cured. To make sure she doesn't end up eating anyone, she often sleeps to combat against her hunger. And in the process, she can recover her energy and be ready for combat.
Nezuko's Demon Mode
Nezuko's Cute Mode
This anime teaches us that criminals in the real world are human just like you readers and I. The same can be said about the demons despite not being, well, human anymore.
They aren't given a choice on who they are as they have to feast on human flesh and show off as intimidating towards others in order to survive.
If they don't, they'll die; just like how some criminals may end up dead if they don't take on the kind of actions they commit.
However, their actions don't justify them as being granted total mercy. Tanjirou has to suck it up and kill any demon he comes across.
But he can show sympathy to some as he realizes that he's taking out not just demons but their own personal lives away. In fact, he even prays for them to have a better life in their next lifetime.
He understands some of them as individuals that are suffering to survive; even if they display as evil beings from the outside.
And of course, there are those with highly corrupt mindsets that take pleasure from what they do. In which case, Tanjirou wouldn't show as much sympathy for them.
Justice must be served or else crime would spread even more rapidly. Thanks to his disciplinary training, he is capable of fulfilling his duties as a proper demon hunter.