Rui lived as a demon for a little less than 20 years.
Li Rui, a Mao Confidant Who Turned Party Critic, Dies at 101 - The New York Times.
Rui (累) was born in a very weak and frail human body many years ago, but reborn as a Demon he is a member of the Twelve Demon Moons and holder of the lower moon five. He is the founder of his Spider Demon Family and assumes the family's youngest position as a child.
While we only saw two lower moons in action (three if you count Kyogai), Rui's the only one that was taken down by someone who wasn't part of the main cast. It makes you wonder why he was rated as lowly as he was, as you could argue, he was stronger than Enmu.
Giyu actually got rid of Rui fairly easily given what a difficult time Tanjiro had fighting with him, and that's why fans can say definitively that Rui is one of the characters Giyu can — and did — defeat.
Although Zenitsu managed to overcome Rui's elder brother, it's unlikely he'd be able to do the same with Rui. Given that Rui is one of the Twelve Demon Moons, he's an incredibly powerful creature — one that almost kills Tanjiro, who's more capable than Zenitsu is when it comes to dispatching demons.
Overall Abilities: As one of the Twelve Kizuki, Rui was one of the strongest demons in existence. This strength easily surpassed that of other demons, since he was easily able to conquer and cohere numerous demons of Mount Natagumo and force them to work for him and become members of his family.
Rui Ayaki (綾木 累, Ayaki Rui), better known as Rui, is an antagonist in Demon Slayer: Kimetsu no Yaiba and the main antagonist of its Natagumo Mountain Arc. He was Lower Rank Five of the Twelve Kizuki, although it was later revealed that his true power was actually much greater.
The next day, she and her older sister attempt to descend the mountain but found their path blocked by Rui himself. Daughter, knowing the consequences, quickly re-joined his side and later watched as Rui tortured his sibling and left her to die.
ENMU was accredited by the North Central Association of Colleges and Secondary Schools as a four-year liberal arts college in 1947. Graduate work leading to the master's degree was added in 1949, and the institution was officially designated Eastern New Mexico University in 1955.
Over a century ago, Doma held the position of Upper Rank Six ( 上 じょう 弦 げん の 陸 ろく , Jōgen no Roku?), and during that tenure, he turned Gyutaro and Daki into demons and introduced them into the Twelve Kizuki.
He has three younger siblings, one brother, and two sisters.
Surprisingly, Zenitsu is the oldest compared to Tanjiro, Nezuko, and Inosuke. What's even more surprising is that even at 16 years old, his cowardly nature makes him seem like the youngest out of the four.
Rui is a Portuguese male first name, also spelled Ruy. It has the same origin as Roderick and Rodrick. It is also a unisex name in Japan.
Rui was the lower-rank five in the kizuki. He caused a good bit of trouble for Tanjiro and Nezuko, so much that their latent abilities were drawn out. If Giyu never arrived on the scene, they would have been defeated.
Meaning:Famous ruler. Rui is a boy's name with Portuguese origins. Meaning “famous ruler”, Rui is a simple but strong name that's a popular choice for those with ties to the Iberian Peninsula. Rui derives from the name Rodrigo but has since taken on a life of its own.
As a result, Tengen Uzui has to deal with the moniker of being the least powerful Hashira around. Of course, that's not the worst thing in the world, as all Hashira are strong. He's still incredibly powerful and can give any demon a run for their money.
Akaza was also one of Muzan's favorite demons out of all his subordinates. The reason behind this is Akaza's extreme loyalty to his master. The Upper Rank Three demon was always sent away on special missions, something the Upper Rank 1 and 2 were often denied of.
2) Tanjiro Kamado
His ability to perform moves from the Breath of the Sun and the activation of the Demon Slayer Mark puts him leagues above the likes of Rui. Tanjiro would beat the Lower Moon demon with ease using his newfound powers.
He is the former Sound Pillar and retired due to injury after fighting Upper Moon Six, Daki and Gyutaro.
When facing Kaigaku during the Infinity Castle arc, Zenitsu debuts his brand new exclusive Seventh Form to Thunder Breathing. With this, Zenitsu finally has more than one tool in his arsenal and has overcome his own personal doubts and fears.
Yoriichi was born with the Demon Slayer mark and prowess in swordsmanship. His powers were beyond comparison as he defeated Muzan once and had him on the verge of death until he managed to escape.
Sound Hashira
He is the fastest Hashira, and the second physically strongest. Obviously, then, Tengen Uzui is rather proud. He is demanding, fussy, boastful, and prone to selfishness. But he is also ultimately kind and caring, with great love for his three wives as well as the other Hashira.
Unfortunately manifesting his Mark in the battle against Akaza also doomed Giyu to die by his 25th birthday, taking the air out of his survival.