Rui Demon Slayer Guide

Rui Demon Slayer Guide: Everything About Him

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Demon Slayer is one of the most popular manga and anime series of this era. The manga has sold millions of copies, and it has gained much more popularity because of its anime. The best part about Demon Slayer’s anime is that it is a mirror image of the manga.

The studio has brilliantly animated the manga adaptation. The whole pacing of the stories and character design is the same. While the main characters of Demon Slayer are often discussed, in this blog, we will be focusing on the demon, Rui.

Rui is the main antagonist in the Mount Natagumo Arc, which starts from manga chapter 28 and continues for 17 chapters. In the first character poll, Rui was voted number 16th by fans. He was the first introduction of fans to a Demon Moon, which makes him a memorable character.

His powerful Blood Demon Art gave me literal goosebumps. Although he only came in one arc, there is still much about Rui that you might not know. Keep reading to find out the details about this powerful demon, Rui.

Who Is Rui?

Rui Demon Slayer

Rui is one of the strongest demons in Demon Slayer as he is amongst the Twelve Kizuki, and his position is of the lower rank of five. Although it is later revealed that Rui was much stronger than his rank. His age is physically 11-13 years old, but his actual age is unknown as he is a demon, so he doesn’t age.

In Rui’s first proper appearance, he says to Murata, Tanjiro, and Inosuke to not disrupt his family’s peace. He leaves them to battle against his mother. Soon after Rui became a demon, he killed his parents. That led to him missing the bond of family and protection, and because of that, he started creating his own family to form a strong bond.

Rui chose demons to be his mother, father, and siblings. He made each of them drink his blood which changed their appearance and made them look like Rui. Drinking his blood made them much stronger and capable of defeating many demon slayers.

However, each of them lived with the fear of Rui because he was very powerful, and he would torture and even kill anyone who would go against his will.

Rui’s obsession with family and guilt over killing his parents made him develop a very twisted personality. He was even given the special permission by Muzan to make a Spider Family. Rui was only a child, yet he was strong enough to quickly climb the Twelve Kizuki ranks.


Before becoming a demon, Rui was an ordinary human child. He was the only child of his parents. However, he was born with a very frail body. Rui could barely walk, and he couldn’t run. He was so weak that he was not even allowed to go outside. He always stayed indoors, but his parents cherished him with love and care.

Muzan took advantage of his situation by one day entering his room and offering to save him by transforming him into a demon. When Rui became a demon, he was glad about being able to walk but realized he could never see the sun again. Soon, Rui killed a man out of hunger.

When his parents came home and saw the bloody scene, they were horrified. When Rui was sleeping, his parents decided to kill him. His mother stayed in a corner sobbing while his father approached him with a knife. In an instant, Rui killed them.

Rui sat next to his parent’s dead bodies when he heard his mother’s last words, “I’m so sorry for not giving you a strong, healthy body.” He felt a lot of grief and was going through a mental breakdown.

However, at that moment, Muzan entered and encouraged Rui by telling him that it was his parent’s fault that Rui was made to do this. By hearing his words, Rui repressed his guilt and made himself believe that this was not his fault.

Rui: Personality, Appearance, Abilities, and More

Rui Demon Slayer


In his demon form, Rui has a child’s physique because of his short height and slim body. His face is pale white with a row of red dots on top of his right eyebrow, right cheek, and below his left eye. His eyelids are turquoise, his irises are pale blue, and the eyes’ pupils and sclera are red.

Rui has Lower Rank Five written on his left eye, proving that he is one of the 12 Demon Moons. Rui’s hair is white and styled to depict the spider legs. His hairstyle is a perfect symbol of his Demon Art, similar to that of a spider. When Rui was a human, his body was almost the same size as in his demon form. He had dark black hair and the same hairstyle. Rui had dark blue eyes and facial features very similar to his father’s.


On the face, Rui seems to be a calm person as he talks in a gentle tone. Rui appears to be very cool-minded throughout his fights and doesn’t make any jokes to the opponent. During his battle with Tanjiro, Rui only speaks serious dialogue and doesn’t insult him. His personality is very serious as his facial expression rarely changes except when he is really angry or touched.

Although Rui has lived for years, his personality is still of a child as he hasn’t moved on from his want for parental love. After experiencing his parent’s attempt to kill him, Rui thought his parents were probably imposters as true parents would never do this to him. He became obsessed with having strong family bonds in which each member would follow their roles.

He believed that any member who did not fulfill their roles, following his instructions and listening to him, should be killed.

Rui desperately wishes to have strong bonds, but his perception of a family and strong bonds are disturbing. Rui only believes that strong bonds can be formed by instilling fear in others. This is why Rui is seen abusing and torturing his family members if they ever do anything against his will. If they accidentally reverted back to their previous form, Rui would torture them.

Rui is very sensitive about the topic of family. When Tanjiro calls his family bond “fake,” he becomes furious and orders him to take his words back or else he will torture him to death.

Moreover, when he sees Nezuko protect Tanjiro by letting herself get cut, Rui becomes highly touched. Rui gets triggered to have the same bond with Nezuko and even offers to let Tanjiro live if he hands over Nezuko to him. Saying that he will forge a “bond with terror” with Nezuko.

Rui had lost all his human memories, but the emptiness and longing for his parents remained in his heart. He so desperately tried to have family members who would love and protect him. Rui would even sit with his spider family members with empty crockery to replicate dining with a family.

Rui used the most toxic and extreme measures of having strong bonds. When one of the spider family members attempted to escape the mountains, he caught her, severely tortured her, and left her in the sun to roast to death. Instead of using love and care, Rui used fear to make his so-called family stay with him.

Rui was an antagonist and a brutal murderer. Still, deep down, he was a lonely child who only wanted to be loved and protected. During his human life, he often felt lonely seeing others children play together while he had to stay alone in his bed. He had no siblings to play with, so he made many siblings in his make-believe family to remove his loneliness.

Rui lost his human memories, but his childhood loneliness and emptiness never left his heart. All his life as a demon, he was trying to bring back bonds that he had severed with his parents.

However, although Rui was mentally unstable and childish, this did not affect his performance in battle. Although he was powerful and mostly had the upper hand in the fight against Tanjiro, Rui did not let himself get carried away.

He carefully would think of each of his moves and charge in accordingly. His wits in battle can be proved by the fact that he quickly decapitated himself right before Tanjiro did, which prevented his death.


Demon Art

Blood Demon Art

Rui’s Blood Demon Arts is thread manipulation. He uses his cells to produce and manipulate threads like spider webs. He makes these threads from his fingerprints, and they are very sharp. These threads have cut the whole bodies of many Demon Slayers instantly and had even cut Tanjiro’s Nichirin Sword. Rui can make these threads much stronger by adding his blood to them.

Cutting Thread Cage

This ability enables Rui to create a cage-like web that completely covers the opponents, leaving them no space to dodge and cutting them into pieces.

Cutting Thread Rotation: Rui produces a rigorously rotating wheel of thread that slashes the opponent once it reaches them.

Murderous Eye Basket

This technique is similar to the Cutting Cage Thread. A sphere-shaped cage of threads is made around the target, which keeps getting smaller until the target Is slashed.

Demonic blood and Cell Manipulation

His Demonic Blood power is similar to Muzan. Rui could share his powers with other demons and make them stronger through it by making them drink his blood. This also allows him to render their appearance and make them look similar to others. This is why Rui’s family members have physical traits similar to Rui. Moreover, each has spider-like abilities identical to that of Rui.

Super Strength

Rui is shown to have excellent and demonic strength when he uses his punches and kicks to beat up Tanjiro. Tanjiro bleeds each time Rui lands a blow on him which shows that Rui has excellent physical strength.

Intensified Durability: Rui’s body seems small, but it is very durable. When Tanjiro tried to cut his neck, he could not even put a small mark on it because it was so thick. Tanjiro realized that Rui’s neck skin is much thicker than his father’s. Rui also admitted that his skin is much more durable than his threads. Even though his threads are very sturdy.

Regeneration: Rui had extraordinary regeneration abilities. Like other demons, he would get regenerated within a second of being wounded.

Limitless Stamina

Every demon has been shown to have unlimited stamina. No matter how much they fought, they never felt tired. Rui also has excellent stamina. Throughout the battle with Tanjiro, he shows no signs of being tired or breathless. Undoubtedly, Rui is one of the strongest demons as he was one of the 12 Demon Moons. According to an official fan book, Rui’s strength was equivalent to that of the Lower Rank One and Two.

Moreover, this estimate of his strength is after him having his powers shared with his family members. Rui’s powers did not return even after his family members were killed, showing that they cannot be returned once Rui shares his powers.

If Rui did not share his powers with others, he would be much stronger than he currently was and could have put up a good fight against Giyu. Rui remained at lower rank five and not higher because he did not care much about ranks or being powerful. All that mattered to him was having strong bonds, and he mainly used his powers for that purpose only.

Last Moments

Rui Last Moments

After being decapitated by Giyu, Rui regains his memories as his soul departs from the world. Even though his physical condition wasn’t good, Rui remembers that his parents were always there for him. He also remembered the words of his father before killing him, in which he said that they will suicide after killing Rui and join him.

Rui realized that his father was atoning for Rui’s sin of murder by killing Rui himself. This made him realize that his parents truly loved him, and Rui deeply felt grief for killing them.

Rui saw the sight of Tanjiro covering Nezuko, although he could barely stand up. He walked towards them with his decapitated body, saying, “It was simply out of my reach, no matter how I strained to get my hands on it.” Accepting how badly he wanted a true family bond like that of Nezuko and Tanjiro, he could never achieve it no matter how hard he tried.

As Rui was dying, he felt incredibly guilty about the people he had killed and realized he could not meet his parents after death because he would go to hell. Surprisingly, when he goes to the afterlife, Rui’s parents meet him and hug them, telling them they will be with him whether it’s hell or heaven.

Meeting his parents and hearing their words makes him cry tears of joy, and his human appearance returns.
While his soul is departing, Tanjiro smells enormous grief from Rui, which makes him feel sympathy for him.


Question: How did Rui Not Die from Being Decapitated by Tanjiro but Die when Giyu Beheaded Him?

Answer: When Tanjiro beheaded Rui, Rui had already decapitated before Tanjiro’s sword touched his neck. However, when Giyu decapitated him so fast that Rui did not have the time to act on it before he did.

Question: Who is the Voice Actor for Rui?

Answer: Rui’s voice actor in the anime is Koki Uchiyama. The same voice actor for popular anime series, including Kei Tsuihishima from Haikyu!! And Amakusa Shirō from Fate/Grand Order.

Question: Did Muzan Like Rui?

Answer: Rui was the favorite lower rank demon of Muzan. He gave him a surplus amount of blood, which made Rui very strong and capable of killing many demon slayers. He even granted him the special permission to transfer his power to other demons by giving them their blood. Muzan also seemed to care about Rui, showing concern over him being sickly.

Rui Demon Slayer Guide: Final Thoughts

Before Rui, fans regarded demons as horrible, human-eating creatures who were selfless and did not care about anyone. However, Rui introduced us to a demon moon’s struggles and sad background story. It showed that even the most horrible demons were once normal humans and wanted a simple, happy life they could not have.

Hearing about Rui’s life story made viewers understand that even demons were not as evil as they have become and feel sympathy for them. Rui seemed like a ruthless maniac, but he was not as complex of a character. Instead, behind those dangerous webs, sadism, and fierce eyes lay an inner child that only wanted to be loved and attention.

Rui made the mistake of killing his parents out of self-defense. He regretted this action his whole life without even remembering his parents.

Rui remains one of my favorite demons from demon slayer because it taught me how important it is to acknowledge the good things in life. He also made me realize that no matter how scary a person may seem, there is a reason behind why they have become this way.

Rui was an excellent Kizuki. He lived up to his demon moon title because he could kill many demon slayers and had awe-inspiring strength, techniques, and combat skills.

If Rui was more focused on achieving power, he would likely have quickly climbed up the ranks of the lower six Kizuki. We could only see Rui in one arc, but it would have been interesting seeing him grow and become stronger if he had lived.

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