The demon slayers successfully defeated Muzan.
Gyomei used his weapon to hold him back while Sanemi, Giyu, and Tanjiro used their Breathing techniques to attack him. With the collective efforts of every member of the Demon Slayer Corps present there, Muzan turned to dust as sunlight came in contact with his body.
Muzan keeps attacking the two Demon Slayers with his tendrils with Tanjiro falling over multiple times due to him not being able to his surroundings. Suddenly the Love Hashira Mitsuri Kanroji drops through the ceiling and stops Muzan's assault by using Love Breathing, Sixth Form: Cat-Legged Winds of Love.
Muzan's experiment on Nezuko worked out exactly as he'd hoped, but unfortunately for him, he picked the wrong family to mess with, as Tanjiro joining the Demon Slayer Corps is what ultimately led to Muzan's defeat and death.
The only character who was stronger than Muzan was Yoriichi. He almost beat Muzan before splitting his body into 1800 parts in an attempt to escape.
Sanemi managed to survive the battle against Muzan, if just barely. Unconscious and straddling the edge of death, Sanemi chose not to go to Heaven with his siblings, but to lovingly join his mother in Hell because she'd killed most of her children after she became a demon.
However, in the Demon Slayer manga Muzan reveals his motivation for attacking the Kamado family. It turns out that Muzan attacked the Kamado family and specifically turned Nezuko into a demon in an attempt to create a demon that would be able to withstand being in the sunlight.
Since he didn't know anything about the Blue Spider Lily medicine, he needed others to find the plant for him by happenstance. This is the general reason why Muzan turned Nezuko into a demon. More specifically though, was the fact that Nezuko was of Kamado blood.
The only thing he's weak to is the sun. That is why he turned other humans into demons and spread his blood so that one of them might find a solution against the sunlight, so he can become truly perfect.
After various battles within the Dimensional Infinity Fortress the remaining Upper Moons are killed by the hands of various Demon Slayers. The last member, Upper Moon Four Nakime, ends up being killed by Muzan Kibutsuji himself to stop the Dimensional Infinity Fortress from being controlled by his enemies.
Upper-Rank Five: Gyokko
As a fellow artist, Gyokko became distracted by Haganezuka's dedication to sword-polishing and opted to hold off on finishing off a wounded Muichiro. Tokito then manifested his Mark and effortlessly decapitated Gyokko with Mist-Breathing, Seventh Form: Obscuring Clouds.
The two known demons who broke free of Muzan's curse are Tamayo and Nezuko. Tamayo was able to break free of the condemnation when Yoriichi fought Muzan, nearly killing him in the process. During this weakened state, Yoriichi let Tamayo go, free her from Muzan, and free her from the curse.
Unfortunately, Gyutaro spots Inosuke and stabs him right through where his heart should be with a sickle imbued with deadly poison.
Thanks to Somiyoshi, and later on Tanjuro who passed it down to Tanjiro, the world is left with a weapon to defeat Muzan Kibutsuji, long after Yoriichi passed away. Those are ultimately the role of Tanjiro's father, Tanjuro Kamado, in the story of the Demon Slayer.
In her final moments, she apologized to Inosuke for failing to protect him and tosses him into the river as an attempt to save his life. She was ultimately killed and eaten by Doma, who claimed to have devoured her to the bone.
Tanjuro Kamado a recurring flashback hero from Demon Slayer : Kimetsu No Yaiba. He was the husband of Kie Kamado, and the father of Tanjiro, Nezuko, Takeo, Hanako, Shigeru, and Rokuta.
In the Demon Slayer Corps, the Hashira is a group of the strongest and most reputable swordsmen who have defeated members of the Twelve Kizuki. Yet, for some reason, Tanjiro Kamado, the series' protagonist, never becomes a Hashira.
The explosion, which was enhanced by spike traps, manages to injure Muzan. Before he is able to regenerate fully, Tamayo appears and uses her Blood Demon Art to keep him in place, while using a drug that can turn him into human. Using this opportunity, Gyomei Himejima appears and destroys Muzan's head.
1) Kyojuro Rengoku
Unfortunately, Rengoku was killed by Akaza, the Upper Moon 3. This took place when he, along with Tanjiro, Zenitsu, and Inosuke, boarded the Mugen train to investigate cases of missing people.
Many Kimetsu no Yaiba fans deduce that Yoriichi is Tanjiro's father, but that isn't the case. However, Yoriichi is responsible for teaching Tanjiro's ancestors the Hinokami Kagura, which has been passed down for generations.
During Tanjiro and the rest of the Hashiras' showdown with the Demon King Muzan, Tanjiro is mortally wounded and dies. At the same time, Muzan receives a particularly fatal lil' booboo himself. As Muzan is about to shuffle off the mortal coil, he uses the last of his powers to turn Tanjiro into a demon.
Muzan, the King of Demons, is the strongest and also the primal demon in the world of Demon Slayer. Consuming his blood is enough to turn you into a powerful demon. He can control all the demons in existence, with only people with strong willpower like Nezuko being an exception.