Between Nezuko, Lady Tamayo, and Rui, it is made very clear that even demons deserve some love in the world of Demon Slayer. Of these three different characters, Rui is easily the most villainous. During his time on screen, Rui taunts, endangers, and nearly kills the characters that fans of the series have learned to love the most.
Still, Rui has managed to earn fans' sympathy in a way that few other anime antagonists ever have. With this in mind, it becomes a fun mental exercise to imagine Rui as a hero, facing off against other villains in the same way anime protagonists so often do. The list matches Rui up against five anime villains that he could defeat, and five that would force him to endure a few training arcs before he could put up a real fight.
10 Rui Beats Isabella (The Promised Neverland) With His Blood Demon Art
Isabella may be one of the most terrifying anime antagonists ever put to screen, but Rui is not far behind. Though he is the weakest of the twelve demon moons, his association with spiders is something that will give viewers chills while Tanjiro and his friends work to defeat the powerful demon.
In terms of physical strength, Rui never exhibits much more strength than Isabella does throughout the first season of The Promised Neverland. Still, Rui is in possession of some powerful blood magic that he could use to easily dismember Grace Field House's resident mother.
9 Frieza (Dragon Ball) Beats Rui With His Powerful Ki
Frieza has grown immensely as a warrior throughout the lengthy run of the Dragon Ball franchise. In fact, his strength as a warrior can be tracked through the many different character designs that he has had since his introduction in Dragon Ball Z.
When Rui is defeated in Demon Slayer, Giyu Tomioka quickly removes his head with a single blow. Giyu may not be the average human, but he is nowhere near the speed or strength of Frieza. The Dragon Ball antagonist would most likely be able to dispatch Rui with his lightning-fast Ki blasts without ever having to sully his hands with the demon's blood.
8 Rui Beats Reiner (Attack On Titan) With His ODM-Like Mobility
Though it isn't entirely clear whether Rui would be able to cut through the Armored Titan's shell with his demon blood magic art, Reiner's habit of diving headfirst into most of his conflicts would surely put him at a disadvantage against Rui.
Rui demonstrates the ability to mimic the power of flight using his webs in the first season of Demon Slayer. The way he moves through the air is similar to the way Mikasa and Levi are able to mimic flight with their ODM gear. With this, Rui is able to navigate his way around the armored titan's body and use his webs to cut through the weak points in Reiner's armor.
7 Meruem (Hunter X Hunter) Beats Rui With His Nen & Physical Strength
The combination of Meruem's physical durability and Nen should be enough to stop Rui's blood magic art from having any real impact in the battle between these two anime villains.
If his defensive strengths aren't enough, then his physical speed, strength, and agility would surely make up it. The world of Hunter X Hunter is full of characters that defy the physical limitations of the human body in ways that no character in Demon Slayer ever has. Meruem wins this fight hands down.
6 Rui Beats Grell (Black Butler) With His Superior Attack Range
Rui's demon blood art and Grell's chainsaw scythe are similar in their ability to cut through nearly anything. The only difference between the two weapons is the versatility of Rui's spider webs.
The battle between these two villains may be one of the most balanced match-ups on this list. Grell's downfall would be their overconfident and flamboyant personality. The Grim Reaper's habit of talking over every other character they share a scene with would surely infuriate Rui and cause him to lash out with all his strength before Grell was fully prepared for the fight.
5 Utsuro (Gintama) Beats Rui With His Swordsmanship
The Samurai in Gintama share a lot in common with the demon slayers that roam through Japan in Demon Slayer. Much like Giyu Tomioka was able to behead Rui in large part because of his incredible swordsmanship, Utsuro could easily defeat Rui as long as he had access to a nichirin blade.
Even if Utsuro didn't have a nichirn blade, Rui would have difficulty killing the immortal villain. The Gintama antagonist may not be the most durable, but he has proven that he is nearly impossible to kill. This immortality would give Utsuro plenty of time to search the world for a nichirin blade that was capable of defeating Rui for good.
4 Rui Beats Tsukasa (Dr. Stone) With His Magical Strength
Tsukasa is without question an intimidating and threatening foe in the world of Dr. Stone, but if the science-centric plotting of the show tells viewers anything it should be that the strongest high school primate is nothing more than an incredibly strong human.
Rui is capable of dismembering humans with training and weaponry that Tsukasa would never have access to after being awakened in the new Stone World. Without any weapons of science, Rui could defeat Tsukasa without breaking a sweat.
3 Garou (One-Punch Man) Beats Rui With His Speed, Strength, & Perseverance
Garou is one of the best anime villains introduced in the last decade. One-Punch Man is celebrated by fans in large part because Saitama is able to easily dispatch even the most powerful villains in a single blow. Garou is different though.
The hero hunter is incredible fast, strong, and above all else, has the will to keep fighting even after being pushed to his limit. Rui would definitely test Garou, but as long as he was able to get his hands on a nichirin blade, his speed and strength would make easy work of the demon.
2 Rui Beats Griffith (Berserk) With The Power Of His "Family"
Berserk is similar to Demon Slayer in its focus on the art of swordsmanship when setting up its battle sequences. While at times both shows lean into the supernatural, most of the fights are won by the strongest swordsman.
Griffith is indeed a powerful swordsman, but unless he was able to tap into the power he obtained after transforming into Femto, Rui would surely be able to defeat him using his demon blood magic art. While it would be a close fight, until fans of Berserk can prove that Griffith is as strong a swordsman Giyu Tomioka of Demon Slayer, the silver-haired swordsman takes a loss against Rui.
1 Liebe (Black Clover) Beats Rui With His Anti-Magic
The devil that gives the protagonist of Black Clover his strength is uniquely equipped to deal with Rui. Much like Shinobu who was able to invent a poison that allows her to catch demons off guard, Liebe would make Rui sweat without ever having to raise a blade against him.
The reason Asta is so powerful in Black Clover is in large part due to the fact that Liebe has granted him his anti-magic abilities. If Liebe was able to carry his anti-magic into the world of Demon Slayer, Rui would be nothing more than an angry little boy.