After Season 3: Entertainment District, Demon Slayer fans are undoubtedly amazed at witnessing Nezuko’s demon power. It was the first time that Nezuko exhibited her demon powers to its fullest – easily overpowering an Upper-Rank demon. Fans might be asking: what exactly are Nezuko’s demon abilities? Why is she so strong?
It is natural to wonder what demon powers Nezuko has, because she easily defeated an Upper Rank Six Demon, Daki. After all, being an Upper Moon means that a demon is considered very strong. Their strength earned Muzan Kibutsuji’s recognition. Upper Moon demons are the equivalent of Hashiras. They are the elite group of demons. The Upper Moons have been mentioned a lot of times in the series. They have already killed Demon Slayer members in the past, including Hashiras. There were also demons who have the goal of being one of the Upper and Lower Moons or the Twelve Kizuki. Some of them even pretended to be one like Susamaru and Yahaba.

To answer the question about Nezuko’s powers, take note that it will only refer to what the audience has seen so far in the anime. Manga spoilers are not included.
Read More: Why Can Daki Go to Heaven While Gyutaro Cannot?
Physical Strength
Even when Nezuko has just turned into a demon, she already exhibited supernatural physical abilities. This was seen when she attempted to fight against Giyuu Tomioka to protect her brother Tanjiro. She did not need to train to be strong.

This was shown again when both Nezuko and Tanjiro fought against their first set of demons. Nezuko kicked the Temple Demon’s head off his body easily.

When she was fighting Daki, she was on her full demon power. She was notably physically stronger than Daki herself, as Daki seemed to rely more on her obi fabric to attack. Nezuko did not need to rely on anything; she has the physical strength. She was able to overpower Daki just by her kicks.

Supernatural Speed
On top of Nezuko’s enhanced physical strength, she is also able to show an unnatural speed. She was able to catch up with Susamaru’s ball attacks like a speed of lightning. When she was fighting Daki, one could get an impression that she could teleport because of how fast she was. Daki could not even react on time.

Physical Size Manipulation
Nezuko can also alter her physical height and size at will. This was first seen when she was urged by Tanjiro to get inside the basket so that she will be carried. This was seen again when Kanao attempted to attack her, and Nezuko tried to escape by shrinking. This gives the audience a chance to see little Nezuko.

When she unleashed her full demon form, her physical size grew into that of an adult’s. It indicated that this adult form will come out once Nezuko does not hold back on her demon powers. This advanced form seemed to give Nezuko more strength and near invulnerability. It also gives her a sense of familiarity and expertise upon using her demon powers.
Nezuko has a horn protruding from the side of her head, cracks around her eyes, and popping veins from her forehead. She also has red vine tattoos surrounding her legs and arms.

Regeneration
Nezuko has shown the ability to regenerate her body parts once it was cut off. Initially, it was slow when they were first fighting against Susamaru and Yahaba. She got overpowered due to this, but this was just because Nezuko is just starting to use her demon powers. This is prior to her advanced form where she was able to use them with ease.

Hence, when she was in her advanced form, her regeneration was quick. Daki even noted that Nezuko’s regeneration is faster than hers. This regeneration allowed her to heal her wounds at an instant, so Daki’s slashes towards her were almost nothing.

Blood Control
In relation to regeneration, Nezuko is able to control her blood when she is in her advanced form. When Daki slashed her body into pieces, Nezuko was still able to keep her body parts connected with the use of blood. This allowed her to reattach her body parts with ease. The blood can also be related to her regeneration power, so that her severed body parts can return quickly. Daki was even shocked by this ability.

Blood Demon Art: Pyrokinesis
Every demon in Demon Slayer has their own unique set of abilities. These are called: Blood Demon Art. Demons will have to perfect these abilities in order to become part of the Twelve Kizuki.
Nezuko’s Blood Demon Art is related to creating fire. Interestingly, it is similar to Tanjiro’s new Breathing Style technique: Hinokami Kagura, or the Sun Breathing Style. The Kamado siblings were able to use abilities related to fire probably because of their family. It is important to note that their father, Tanjuro, used to perform a ritual to the sun. He also taught Tanjiro about the Sun Breathing Style technique with all the movements and necessary breathings.

Nezuko’s Blood Demon Art is pyrokinesis, in which she had first shown this when she was trapped in Rui’s Blood Demon Art spiderwebs. Her fire was able to severe through Rui’s sharp and firm ties.

Her blood can also constitute her pyrokinesis power. When Daki was splattered with Nezuko’s blood, the former’s body was engulfed in flames. This led to Daki being terrified, as she most likely have a trauma of getting burnt because of her past.
See More: Why Can Daki Go to Heaven While Gyutaro Cannot?

Nezuko’s flames are not always dangerous. It also has the ability heal and cleanse a poison. She was able to save both Tengen Uzui and Inosuke from death because of this.

Hence, Nezuko can control her pyrokinesis if it is intended to be harmful or not. This can be easily misunderstood by everyone at first. This led to a rather hilarious scene of Suma, one of Uzui’s wives, freaking out when Uzui was engulfed in flames.

Gaining Strength by Sleeping
Demons would consume humans to become stronger and to sustain themselves. This was not the case for Nezuko. She only sleeps to recuperate herself. Once she used all of her strength, the longer her sleep will be.

This is strongly connected to her strong willpower to not eat humans. This is rooted from Urokodaki’s message to her when she first slept as a demon. “All humans are your family. Protect humans.”
This was shown in an incredibly powerful scene wherein a Hashira, Sanemi, sliced his arm open to test Nezuko’s control. She remembered Urokodaki’s words to her and Tanjiro to be able to resist Sanemi’s blood.

The only time she has lost control is when she is in her advanced demon form. It is understandable because it is her first time to use her full power. Thankfully, Tanjiro was there to help her calm down.

Considering all of Nezuko’s demon abilities so far, it is no doubt she is a very strong demon. It can technically rival those belonging in the Twelve Kizuki. Gaining energy through sleep alone is something commendable as well. Who knows if she still has more abilities she has yet to show?
As for the question on why she is so strong, there have been no answers yet presented by the anime. The audience will have to find out in future installments!