The muzzle serves as a representation of Buddhist practices. First, it gags Nezuko, preventing her from speaking like a Buddhist monk's vow of silence, but it also is there to suppress her desire to eat humans. Through a Buddhist lens, Nezuko's muzzle is the symbol of a Buddhist monk.
However, in later volumes, the muzzle is removed and she gains the power of speech in volume 22 then remembers everything and gets her human thoughts again and remembers her name, albeit very broken due to not speaking for more than two years.
While Nezuko does go a vast majority of the series without speaking, she does eventually gain this ability in coincidence with another important ability.
In the manga, Nezuko conquers the sun, so she does not need the muzzle as she can also now speak and control herself a bit more.
Due to her demon abilities, Nezuko can change her size/age and appear “mature” in a slightly older form or can even make herself look younger and smaller than a 12-year-old. Anime is weird and demon stuff only makes it weirder.
A few episodes later, Nezuko is 14 years old, however, physically, she has not aged since that faithful and tragic day, and that's something that will not change unless Tanjiro finds a cure.
Demon Slayer: Analyzing the concluding chapters to ascertain Nezuko's love interest. Nezuko marries Zenitsu Agatsuma in the Demon Slayer series. Let's understand how we arrived at this conclusion. The concluding arc of the manga is focused solely on the fight taking place between the demon hunters and Kibutsuji Muzan.
Nezuko and Bipolar Disorder Nezuko's caring personality changed after her family was slaughtered by the home invasion. Nezuko developed Bipolar Disorder due to the mental and physical stress that was put in her body.
With this in mind, if Nezuko had also been murdered by Muzan, Tanjiro would have no reason to be empathetic toward demons. Her transformation gave him a perspective of both demons and humans, but without Nezuko becoming a demon he would have no reason to take their feelings into account.
If Nezuko were to taste blood, it's likely that she would lose control completely, forcing Tanjiro and other demon slayers to kill her. So the bamboo gag really protects Nezuko as well as the other humans the slayers may encounter on their journey.
However, the trait that sets her apart from all other demons is the fact that she has the ability to conquer the sun, prompting the Demon King to call her the "chosen demon". Abnormal Demon Physiology: As the "chosen demon", Nezuko has several unique demonic traits that set her apart from all other demons.
However, she wasn't immune to the sunlight initially, as she got burned badly at first. So, in conclusion, her coming from a Sun Breathing user's lineage and not relying on human substance are perhaps the reasons for her immunity.
After becoming a demon, she seems to have regressed to the mental state of a small child (or even an intelligent pet) and is mostly non-verbal. In contrast, most demons seem to be at human-level intelligence and can talk, even the “lesser” ones.
Moreover, Nezuko has an extraordinary growth rate, as shown multiple times when she grows stronger without any training or consuming humans.
Unlike other demons who survive on blood, Nezuko never really needs it, and she doesn't even consume human food either. Moreover, Nezuko has never shown any signs of undernourishment as she is always ready to assist her brother with her overwhelming strength and deadly Blood Demon Art.
Ultimately, Nezuko survives and finally turns into a human after being stuck as a demon for so long. Despite turning into a human, she's one of the prime reasons why Tanjiro could defeat Muzan, even after almost being turned into a demon himself.
Nezuko proceeds to instantaneously regenerate her arm, which was cut off as well, leaving Daki uneasy as she realizes that her regenerative abilities are on par with an Upper Rank Demon.
Therefore, it is safe to assume that Zenitsu and Nezuko end up together and have kids in the future. This is proof that Zenitsu loved Nezuko and she too came to love him at some point in time.
To sum things up, Tanjiro died fighting Muzan and was revived within seconds due to the transfer of blood from the Demon King to Tanjiro. He turns into a Demon and Kanao injects a certain medicine made from Wisteria flowers that turns him back to a human.
8 Sexualizing Daki and Nezuko Is Uncomfortable
The most egregious example is Daki, though Nezuko also gets her moments of weirdly sexualized costume and plot choices. Daki is highly sexualized despite being biologically thirteen years old.
After the battle, Tanjiro returns home with his sister and friends. Later it is revealed that he married fellow slayer Kanao Tsuyuri.
It is confirmed in the Volume 23 extras that Inosuke and Aoi did eventually end up together and that they have two great-grandsons, one of which is Aoba.
Eventually Zenitsu and Nezuko would marry and start a family as evidenced by their descendants.