What If yoriichi Became the Demon King? An Alternative demon slayer Story

We all know that Muzan is the Undisputed Demon King, and because of him, we have the amazing series we know as demon slayer. Meanwhile, yoriichi is undoubtedly the strongest swordsman of all time. So, have you ever wondered what would happen if yoriichi became a demon? Scratch that, let's think of something bigger—what if yoriichi became the Demon King?

 

The Beginning: yoriichi's History

 

Surprisingly, not much changes at the beginning of the story, especially yoriichi's history. As always, yoriichi was born in the middle of the Sengoku period with his twin, Michikatsu Tsugikuni. yoriichi had a mark on his forehead that his father deemed unlucky, but this gave him the ability to see through the transparent world.

 

As he grew up, he met Uta, an orphan who would eventually become his wife. He was expecting a child, but on his way home after trying to find a midwife, he saw that Uta and their unborn child were killed by a demon. He was so struck by this tragedy that for 10 days straight, he did nothing but hold her corpse in his arms. Eventually, this event led him to become a demon slayer. Because of his raw talent, he eventually became the strongest and mastered the Sun Breathing technique, which gave birth to the five fundamental breathing styles.

 

The Betrayal and Banishment

 

In one of his journeys as a demon slayer, yoriichi saved Sumiyoshi and Suyako Kamado, Tanjiro's ancestors, and they became really good friends. His most fateful encounter was with Muzan himself, where he sliced and diced him up so badly that Muzan almost died and got PTSD. Michikatsu, his twin, eventually met with Muzan and agreed to become a demon, changing his name to Kokushibo.

 

As a demon, Kokushibo assassinated the Oyakata, the head of the demon slayer Corps, and this was the catalyst for a massive change in our story. Because of this betrayal, the other demon slayers demanded that yoriichi take responsibility for his brother's actions and commit seppuku. Lucky for him, the new Oyakata was merciful and decided that yoriichi would be spared and banished instead.

 

The Transformation

 

Now, this is where things get interesting. In the original series, yoriichi continued to independently kill demons and even kept in touch with some of the Hashiras secretly. But in this timeline, yoriichi felt betrayed, and his sense of justice slowly got twisted. He ran off on his own to hunt down Muzan, and his entire demeanor changed from being warm like the sun to cold like the winter.

 

However, before he committed to this manhunt—or demon hunt—he met up with the Kamado family one last time, one of the few people he trusted the most, and showed them the Sun Breathing technique. Sumiyoshi promised that he would keep the Sun Breathing technique alive through the Hinokami Kagura and realized that this would be their last meeting as yoriichi handed them his Hanafuda earrings as he bid farewell.

 

Yoriichi Becomes a Demon

 

Yoriichi's journey was long, and he killed a lot of demons on his way until he finally found Muzan. Of course, Muzan was outright terrified. Imagine seeing the man who almost killed you appear right before your eyes once again. The two fought, and as you can tell, yoriichi easily made Muzan fall to his knees. But instead of killing Muzan, he tried to make a deal.

 

Because of his deteriorating mental health and his outlook on the world becoming totally twisted and dark, he decided he wanted to become a demon to take revenge on the humans who treated him like trash all his life. Even though he was indifferent, Muzan agreed because what else could he do? If he didn't make yoriichi an ally, he was dead. So, he gave yoriichi a lot of his blood in the hopes that he could not assimilate properly and die due to the transformation. But surprisingly, yoriichi transformed into a demon and, because of his hyper physical abilities, was able to instantly regain his consciousness without turning into a total beast.

 

The New Demon King

 

Muzan couldn't be any happier because the one he feared the most was now on his side—or so he thought. After yoriichi became a demon, an Upper Moon meeting commenced, and he was instantly welcomed into the organization, albeit with a lot of tension. Most of the demons hated the new powerhouse coming in because it would mean there's going to be a chance when it came to their rankings, and no one knew this more than Kokushibo himself, the current Upper Rank One.

 

To test his loyalty and knowing their past, Muzan came up with a little twisted game. He ordered yoriichi and Kokushibo to duel for the position of Upper Rank One. Without hesitation, both agreed. yoriichi remained nonchalant the entire time while Kokushibo was full of rage and anger. The fight was fierce but also ended fast because, as we all know, even an 80-year-old decrepit yoriichi almost ended Kokushibo's life but couldn't do it because he died standing. yoriichi won and became the Upper Moon One, but he spared Kokushibo's life in the process because he still had a little bit of compassion left inside him.

 

The Ultimate Betrayal

 

Because of these events, Muzan clearly thought that yoriichi was completely loyal to him. By the looks of it, yoriichi was willing to put everything on the line just to gain power, and this led Muzan to put his guard down. One night, yoriichi requested a personal meeting with Muzan to supposedly discuss plans on how to kill the demon slayers. Suddenly, he whipped out his sword and tried to decapitate Muzan in one go. Luckily, Muzan was able to dodge this surprise attack and went full-on attack mode. He was panicking and scared because not only could he not look inside yoriichi's mind, but he couldn't even activate the curse that comes with his blood.

 

Yoriichi took another opportunity to attack, and the two clashed swords and claws. It was a fight to the death, and Muzan couldn't comprehend why yoriichi wanted to become a demon first before he killed him. It lasted a while, but in the end, Muzan was completely annihilated. He tried to do the same trick where he blew himself up into tiny little pieces, but it didn't work, and yoriichi finally defeated him. The Upper Moons rushed to the room where the two fought and saw that yoriichi was the only one left standing. He declared himself the new Demon King and, instead of trying to find the Blue Spider Lily, decided they would eradicate the demon slayers.

 

The Taisho Era

 

Years passed by, and it was now the time of the Taisho era. Tanjiro Kamado was born. Just like Muzan, yoriichi and the rest of the demons had no luck in trying to find the headquarters of the demon slayer Corps. On the other hand, Kokushibo was full of jealousy, not only because he lost his spot as the Upper Rank One but also because yoriichi became the Demon King. Even he had no choice but to follow yoriichi's orders as the demon second only to yoriichi. He continuously tried to challenge his brother, but not once did he win, and every time yoriichi held back just to save his life.

 

With the news of yoriichi becoming the Demon King spreading like wildfire and proof that demon slayers could, in fact, become demons, it led to a pretty catastrophic outbreak of betrayal cases among the demon slayer Corps. Low-ranking demon slayers who had no loyalty to the Corps, as well as those who were consumed by hate and treated unfairly by society, started flocking to the demon side, and this resulted in their numbers swelling up by the hundreds, if not thousands.

 

The Civil War

 

But there's a disadvantage that comes with this as well. The new demons were much weaker compared to those in the original series because these freshies were turned by demons that were also turned by yoriichi. This means that the concentration of Muzan's blood was not at its purest, resulting in lower boosts when it came to physical abilities as well as more chances of a transformation going completely wrong.

 

Another thing triggered by this increase in demon slayer demons is the fact that older demons, or those who didn't come from any demon-slaying background, hated the newcomers because there's a stark difference in mindset and a lot more. As the days go by and with the new demons outnumbering the old ones, a civil war across demon society looks imminent.

 

Because they weren't affected by the change that much and overall just respected the hierarchy, the Upper Moons decided to align themselves with yoriichi, except for Daki and Gyutaro, who felt indebted to Muzan, as well as Kokushibo, who was secretly flaming up the revolution. In addition, the Lower Moons 2, 5, and 6 joined the traitor side after Kokushibo promised them more power once they had won.

 

A huge battle broke out between the two sides inside the Infinity Castle. Hundreds of demons fought each other to the death, tearing through flesh and bone. During this battle, yoriichi and Kokushibo dealt a lot of damage to their opponent's troops, but it was pretty obvious that the rebels were at a complete disadvantage because they only had Upper Moon One and Upper Moon Two. The rest of the Upper Moons, alongside yoriichi, were having the time of their lives, and the rebels were relying on Kokushibo the entire time to carry them to victory.

 

However, Kokushibo made a grave miscalculation, one that would cost him this entire battle, and it was no other than Nakime. But why is she so important? Well, if you weren't listening, you would have failed to notice that Nakime's blood demon art is quite literally their entire battleground. Yep, just like in the original series, Nakime can control the Infinity Castle itself, and this gives the Loyalists an overpowered advantage.

 

As the battle raged on, the rebels were slowly losing their footing, and Kokushibo could only do so much. In the end, all of the traitors were killed except for Kokushibo, who successfully escaped before they were surrounded. Now you might be wondering, why doesn't yoriichi just chase him since he is the Demon King and must know where every demon is? Well, it's because he doesn't have Muzan's demon manipulation, which allows him to tap into the thoughts of other demons. This is also the same reason why he couldn't quell the rebellion before it went way out of hand.

 

Even though he managed to run away, Kokushibo was severely wounded, and his regeneration couldn't keep up with the wounds he suffered from yoriichi's Sun Breathing. This is interesting to know because Sun Breathing is the only breathing technique that can limit a demon's regeneration, and since yoriichi was the one who created it, well, you already know it's potent as heck. He keeps running and running and eventually ends up in the middle of nowhere in the mountains. As he keeps moving, by pure coincidence and by my omnipotent powers, he eventually ends up at the Kamado household and meets Tanjiro, who is standing outside of their home performing the Hinokami Kagura.

 

Tanjiro's Transformation

 

Now, seeing a demon for the first time, Tanjiro was scared out of his pants and had no idea what to do. However, instead of raging around or, in fact, killing these humans whom he saw, Kokushibo decided that diplomacy was the key to the situation, and it was because of Tanjiro's Hanafuda earrings, the dance, and a scar on his forehead. Yes, aside from reminding him of his brother, Kokushibo realized that these people were affiliated with yoriichi one way or another, and it was too good to be a coincidence.

 

As we all know, since Tanjiro is the kind of person who hears demons out, he agreed to listen to Kokushibo when he said that he wanted to tell his story. He explained his past, how he became a demon, and how he and yoriichi eventually betrayed the demon slayer Corps. However, like the sneaky little demon he is, he added a bit of a twist to the entire thing to make it look like he was the good guy. He explained that he ran away from yoriichi, who eventually became the Demon King because they ended up fighting after Kokushibo tried to convince him to stop all of this nonsense. He also added a little spice, saying that he realized his mistakes when, in fact, he was just jealous.

 

He kept on telling more lies, saying that yoriichi would eventually come for them because the Hanafuda earrings that Tanjiro wore symbolized the last remnants of the Sun Breathing users—Yoriichi's arch-nemesis. Now, if you've watched the series, you can easily notice that these are all just blatant lies, but if you're Tanjiro, you might be convinced, and that's exactly what happened. After an intense back and forth and a lot of talking, Kokushibo finally convinced Tanjiro to become a demon to protect his family. He also asked permission from Tanjiro's siblings and mother, and he promised that Tanjiro would be safe during the transformation.

 

It was a success. Tanjiro had now become a full-blown demon, and with Kokushibo, they trained to control his new abilities. It took a couple of years for this to happen, and during that time, Kokushibo was welcomed into the Kamado household, and he became really close with Tanjiro and Nezuko to the point where he somewhat got attached to both of them. But good times don't always last forever because yoriichi, even after two years, was still sending out search parties to try and catch Kokushibo before he completely messed up everything he worked so hard for.

 

One of these search parties was attacked by a group of demon slayers, and there was only one survivor left. At the same time, Kokushibo and Tanjiro were already out training because it was nighttime, and it was the only time they could go outside. Suddenly, Tanjiro and Kokushibo heard screams and instantly dashed back home. When they arrived, they were met with a horrific scene. The surviving demon, in a bid to get some food and regenerate, ransacked the Kamado household and killed everyone inside. When it saw both of them, it tried to escape, but Kokushibo instantly killed it with one swing of his sword. They were too late, and Tanjiro's entire family was dead.

 

Tanjiro became full of grief and rage, and surprisingly even Kokushibo felt angry. Is Kokushibo starting to change, or are you just full of copium? At this moment, Tanjiro swore to get vengeance on his family and eradicate every single demon from existence, especially yoriichi. Before they could bury the bodies, however, the demon slayer squad that ambushed the search party arrived, and when they saw the situation, they instantly thought that Kokushibo and Tanjiro were responsible. Before they could catch them, however, both successfully escaped, but the one leading the demon slayer squad, Giyu, felt like something was wrong and decided to investigate further.

 

Alliance with the demon slayer Corps

 

As time passed by and Tanjiro finally started to move on in the hopes that he could finally get his vengeance, he and Kokushibo trained more. Eventually, Tanjiro mastered his demon form and even unlocked the Sun Breathing technique through Kokushibo's guidance. His blood demon art is the same as Demon King Tanjiro in the original timeline—biokinesis—where he can manipulate and change his body at will. Tanjiro could also maintain his consciousness much better when in highly stressful situations, meaning that he could use swords gracefully in battle.

 

With that in mind, Kokushibo decided that it was time for Tanjiro to get a proper Nichirin sword, and to do this, they went to the first location Kokushibo had in mind—the former demon slayer headquarters. Remember when I mentioned that Kokushibo killed the Oyakata when he first became a demon? Yeah, because of that incident, the demon slayer Corps decided it would be a good idea to hide their headquarters in a more remote area and abandon the last one that came under attack.

 

As they traveled towards the location, Kokushibo led the way and revealed why it was abandoned, essentially trusting Tanjiro with his past. They reached the ruins of the old headquarters and went through the rubble and abandoned buildings. As they reached the armory, Tanjiro found an old sword and instantly took it. It was still sharp, usable, and most of all, was made with Nichirin. But before they could even collect their thoughts, Giyu and his squad ambushed them. These guys just seemed to be really good at jumping people.

 

Giyu revealed that they had been tracking them for weeks on end. Because of this disturbance, Kokushibo got annoyed and was ready to throw hands and essentially just murder the demon slayers so they wouldn't be a burden anymore. Luckily for them, though, Tanjiro stopped Kokushibo and convinced him to let him take on the demon slayers because it would be good practice. Both sides readied themselves, and one demon slayer took the first move. In the blink of an eye, he was instantly knocked out, and as he approached Tanjiro, they suffered the same fate. They weren't dead, though, just unconscious.

 

It was such a one-sided fight that after a few minutes, Giy