We will discuss about Rui’s backstory in this blog post. Rui was the Lower Moon Rank Five Demon among the Twelve Kizukis. Rui’s story was one of the first long arcs we see in Demon Slayer. The anime features alluring animations and a captivating fight.

Going by personality, Rui was primarily calm and polite. He rarely raised his voice and talked to everyone, whether they were demons or Demon Slayers, in a usual way and with a normal vocabulary.

Rui by TheMightyBattleSquid
Rui by TheMightyBattleSquid

However, his low and guttural voice seemed to hide anger and irritation. During their duel, whenever he talked to Tanjiro Kamado, he was polite and never insulted him or called him a name.

Rui Backstory as a Human

Rui was born into a family with some money many years ago. He had a body that was weak, fragile, and easily stressed. Even walking and breathing were hard for him.

Because of this, he spent most of his life in his home, being cared for by his mother and father, who loved and cherished him even though he was weak.

Rui Backstory | Rui as a human from Wiki
Rui Backstory | Rui as a human from Wiki

Becoming a Demon

One night, Muzan Kibutsuji came up to Rui and said he could “save” him by making him into a demon. Now that Rui’s body was strong, he could move around freely for the first time. But this happiness didn’t last long.

Now that Rui was a demon, he had to eat people to stay alive. This is why he killed a man in his own home. When his parents saw the bloody scene, they were horrified by what their son had done. Later that night, when Rui woke up, his father was holding a knife to his throat and his mother was sobbing nearby.

Rui Kills His Parents

He killed both of them and then went outside to think about what he and they had done. He remembers hearing a story about a man who drowned to save his son. The act of parental love moved him. He thought that his parents were fake because they tried to kill him. He refused to believe that they could even think about killing him.

Rui, after killing her parents.
Rui Backstory: Rui, after killing her parents.

But as his mother was dying, Rui heard her say she was sorry she couldn’t give him a healthy body. This made him think of his father’s last words, in which he promised that he and his wife would kill themselves to join Rui in the afterlife.

Realizing their Parent’s Love

He realised that his parents did love him and were just trying to stop him from becoming a full monster. This made him feel even worse about himself.

Soon after, Muzan showed up and told the young demon that it was his parent’s fault for not accepting his new form. Rui couldn’t handle the weight of what he had done, so he took Muzan’s words as accurate.

Rui Backstory as a Demon

Rui spent most of his time as a demon in the forests of Mount Natagumo.

Over time, he turned into a very powerful demon. He had a lot of Muzan’s blood and a very deadly Blood Demon Art, which was a set of strong, razor-sharp threads that he could throw at will and with great skill. He became one of the Twelve Kizuki’s Lower Five, but he didn’t want to move up in rank.

Rui Backstory Demon Slayer
Rui Backstory Demon Slayer

Rui’s Power Even Impressed Muzan

He still ate people, and Muzan said that he was as strong as Lower Two and Lower One. This made Muzan think of him as a favourite among his servants. Rui spent a little less than 20 years as a demon.

Even though Rui was the one who broke the bond between his parents and, he missed them very much and spent decades trying to re-create their bond with demons. Muzan gave him permission to start the Spider Family.

Rui Making a Family

He found demons on Mount Natagumo and took them in with the promise that the Demon Slayers would protect them.

Once he found them, he took them to an abandoned house that he made his home, gave them a drop of Muzan’s blood to make them stronger, and changed their appearance to look like his. He then gave them family roles, like father, mother, brother or sister.

Even though Rui was the most powerful member of the family, he acted like the youngest son who needed to be protected by everyone else.

Over time, different demons moved in with him and got stronger. Rui’s twisted and poisonous view of family, on the other hand, made it hard for many of the members to get along. Rui thought that his family had to protect him since he was the youngest. He put a lot of pressure on the demons to do this, and when they didn’t, he punished them severely.

Rui Backstory | Rui’s Mother

Rui’s Expectations of a Family

He found some demons, and one of them was a young girl. He made her the mother of his family. Her recent change and memories of being human-caused her to sometimes fall short of his expectations, which he met with a harsh reprimand.

Mother came to fear him a lot and even wanted to die to keep him from finding out that she had failed.

Lower Moon Rank Five
Rui Backstory – Lower Moon Rank Five

Rui met a young demon once when she was being chased by a group of Demon Slayers. He told her that he would protect her if she joined his family. When she quickly agreed to do what he asked, Rui quickly got rid of the Demon Slayers and made her his sister.

This particular demon found out very quickly that his idea of what makes a family was based on cruelty and fear.

Rui Killing Anyone Who Tried To Escape His “Family”

Rui was called to a meeting with Muzan, and her “older sister” told her to leave the mountain. As they ran into the woods, Rui found them. The demon quickly joined him, and he killed the person trying to escape by tying her up in his threads and letting her die in the sun.

Rui Backstory - Rui killing a sibling
Rui Backstory – Rui killing a sibling

His “family” used to have at least nine people, but now only five people, including himself, are left. His “parents,” two siblings, and he, who is the youngest, are all in him.

On another occasion, his “father” was mean to his “mother.” She was scared, so she denied knowing what made him mad, but Rui told her it was her fault that she didn’t know. Only his “father” and “older brother” were okay with him wanting a family, while his “mother” and “sister” were afraid of it.

Final Thoughts – Rui Backstory

Rui’s tragic story started when he became a demon and got the need to eat humans. Before that, he faced a cruel life because he had a weak body, but his parents loved him. We don’t see that with other demons in the series.

Rui’s craving for a family after becoming a demon is tragic.

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About the Author

Logan Rane

Hey, I'm Logan, and I love anime and manga. I could talk about them all day, write about them non-stop, and watch them around the clock. I've watched hundreds of animes and read thousands of mangas at this point in my life - so you could say I'm pretty deep into it all.

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