“Anyone who doesn’t get jealous of other people is just lucky. They haven’t met someone…who has received the Gods’ favor.”

“Someone intense…and vivid who burns everything like the sun.”

“I think…I have met someone like that,” Ai walked in the darkness alongside the Strongest Demon to ever serve Muzan.

“Who?”

Ai smiled, without answering, looking at Kokushibo, in his human form, with only two eyes, “You look much better now.”

Kokushibo stroked his face, getting a feel of it, “It’s been a while.”

“It’s the same as him… or his face is the same as mine.”

“Twins?”

“Yes. In our time. Twins were an inauspicious omen. Moreover, my younger brother Yoriichi was born with a disturbing mark, so his father declared he would kill him.”

“But when mother heard that…her anger was irrepressible…they agreed that he would not kill my young brother and that when Yoriichi reached age ten. They would send him to a temple.”

The two of us had different rooms, clothes, education, food…our uprising was entirely separate.”

“I would evade my father’s eyes and go to play in Yoriichi’s small room. If I gave him my belongings, our father would notice, so I gave him a flute I made.”

“From the time Yoriichi was a baby…he never smiled. And he didn’t speak until age seven. So everyone thought he was deaf. I learned he wasn’t deaf at about the same time. I was practicing my sword swing in the garden. Yoriichi was silently standing in the shade of a pine tree…and that was alone was frightening.”

Ai Senju pressed her lips into a smile, trying to maintain it as she looked towards a courtyard that appeared. There was Kokushibo and his teacher, and besides a tree was a young boy with a mark on the left side of his face.

“I learned he wasn’t deaf at about the same time as I was learning the sword. I was practicing swing, and Yoriichi was silently standing in the shade of a pine tree, and that alone was frightening.”

Ai turned her eyes towards the boy, “My brother is your dream to become the strongest samurai in the land?”

“I was so surprised to hear him speak that I dropped my sword. Then suddenly, he said that he also wanted to become a Samurai. But our parents had decided they would send him to a temple when he turned ten. I wondered if he understood that.”

Ai watched a different memory, one where Yoriichi was holding onto his mother, walking with her.

Kokushibo narrowed his eyes, “I used to think that Samurai risk their lives in battle. So a boy who clings to his mother at the very sight of her could never become one.”

“However, after that…Yoriichi started hanging around and saying he wanted to learn too. My instructor casually told him how to hold it and how to stand. My father’s vassal took a fighting stance and told my brother to strike him.”

“No matter how hard I tried…I couldn’t land a single blow…but in the blink of an eye.”

Ai followed Yoriichi and all four of the strikes, narrowing her eyes, “That’s…quite advanced for someone who tried it for the first time.”

Kokushibo shook his head, walking in the distance, away from memory, “After that…he stopped saying he wanted to become a Samurai. The feeling of hitting someone was unbearable to him. But I wanted to know the secret of his strength…and then one day. He said.”

“Before your opponent attacks, his lungs heave…you need to look closely at the disposition of his bones. The contraction of his muscles and the flow of his blood.”

“That’s Demon Mark…and Transparent World. He was born with it?”

“It took us some time to understand.”

“Instead of talking about swords…I want to play board games or fly a kite with you…is what he said.”

“I…though…” Kokushibo breathed in, “I wanted to master the way of the sword…and that required pain, suffering, sacrifice. But talent had been recognized in me…and I worked harder…the stronger I got. But compared to a child prodigy like I was like a turtle.”

Kokushibo closed his eyes, “Our positions had reversed…now I was the one to be sent to the temple…and my dream of becoming a samurai would never come true.”

“When I was lying on my bed, contemplating, trying to accept the new reality…Yoriichi came to my room and informed me of my mother’s death.”

“When I asked what happened…all he said to ask the servent and that he would depart for the temple. I didn’t understand….”

Ai turned her eyes in the memory, seeing Yoriichi hold a flute in a cloth, smiling warmly at it, “I think of this flute you gave me as you. We may be apart, but I will not lose heart…and work diligently daily.”

Kokushibo walked away from this memory: “That flute was a piece of junk that could only play off-pitch. But he…held it as if it was treasure…and his smile. I found it disturbing since I couldn’t understand.”

“I later read mother’s journal…and it told of how Yoriichi had sensed that father would designate him as heir, so he decided to leave the house. He also had known of mother’s illness…for years she had suffered difficulties on the left side of her body.”

Kokushibo stopped, and memories of Yoriichi holding his mother on the left came pouring in front of him, “The left side…I realized that he hadn’t been clinging to her. She had been weakened, and he was supporting her.”

Kokushibo clutched his chest, “I still remember…even centuries later…the burning jealousy that I felt for Yoriichi’s genius at that moment.”

He shook his head, erasing these thoughts from his mind, “Next few years were serene. I married…had kids…and then years later, when I was at a camp…we were attacked by a Demon. And the one who saved me…was….”

Ai looked at the new set of memories, seeing Yoriichi, though he looked different, sadder, “All that jealous…rage…came rushing back at that moment.”

“He apologized for being late…and because one of my subordinates died. He was a person of faultless character…but I…I wanted to make his skill and strength my own. To the point, I abandoned my family.”

“Later…Yoriichi would teach everyone who wished to learn his sword skills and breathing techniques. But none could match him. He even adjusted the Sun Breathing to their nature and personalities to bring out their power, and more derived forms came out.”

“And with those…came the Demon Marks. I, too, awakened it, but I still couldn’t match the Sun Breathing…I could only use a derived form…Moon Breathing.”

“Then…one day…everyone with the Mark started dying one after the other, and we realized that Mark gave strength in exchange for Lifeforce. I realized I had no future…and hadn’t achieved what I wished to…and then….”

Ai turned around to see Muzan offering him to become the Demon.

“And I…abandoned everyone again…unfettered of all restraints…and so I thought.”

Ai turned again to see Yoriichi, who had gotten older, standing in front of Kokushibo again.

“He transcended the laws of nature…and defeated me again by escaping death at my hands. No one…not even Lord Muzan, could defeat him. Not a single person was able to harm him! He made me feel miserable!”

“Hate!! I hated him with everything I had!!”

Ai had watched Yoriichi’s last strike, nearly killing Kokushibo, but had spared him and taken his last breath. And in anger and hate, Kokushibo cut Yoriichi’s corpse, cutting the flute he gave.

“You are crying….”

Kokushibo ignored her, “Just seeing his face made me sick…even after hundreds of years…what I remember vividly is his face. The thing I wish to forget the most.”

“He’s like unequaled sun…and around him, all humans have no path other than yearning and reaching out their hands…writing in agony…until they become ash.”

Kokushibo looked in the darkness, walking towards the flames of hell in the distance, “I abandoned my home…my wife and children…my humanity…the dream and honor of being a samurai but all that wasn’t enough. He said all those who walk the same path reach the same place. But I never did. I could not see the same world that he did. Why could I not become someone...? Why could I not leave behind anything? Why are we so different? Why was I even born…. Tell me?”

“But that’s not true,” Ai took a deep breath, closing her eyes to hold back her tears, “You…left behind a family…children who admired you. The ones that were so proud of you that they continued your legacy. Every one of them, for generations, became Demons Slayers. That family…is your blood.”

“You were someone…someone from the Golden Generation…someone we, the Demon Slayers, looked up to, and even as a Demon, you were one hell of an enemy, one that we will remember.”

“I can’t answer why you were born…but I am glad you were born. If you weren’t born, then Muichiro wouldn’t have been born, and maybe so many others,” Ai tilted her head, smiling, “So…thank you for being born.”

Kokushibo looked over his shoulder, seeing her smile, “Your smile too….”

He turned around, stepping into the fires of hell, “I hate it.”

Ai grinned, even more, watching as the flames of hell disappeared, and she thought it was over. She closed her eyes, prepared to return when a voice interrupted her.

“Thank you. For accompanying my brother…hopefully, he would find some peace.”

Ai blinked, having heard this voice in memories of Kokushibo, “Mr. Yoriichi?”

A young man with the face same as Kokushibo and a Demon Mark, much like Tanjiro’s, stepped in front of her. His eyes gazed at the flames, “Would you hear me out too?”

Ai parted her lips, nodding, “Yes.”

Infinity Castle,

“Now! Be ready!!”

Tanjiro, Giyu Tomioka, Kyojuro Rengoku, Mitsuri Kanroji, Obanai Iguro, Sanemi Shinazugawa, Genya Shinazugawa, Hyomei Himejima, Shinobu Kocho, Konoe Kocho. Every one of them stood in the place where Ai had trapped Muzan. However, he was nowhere to be seen.

Before, Tamayo had created the medicine that turned Demons into Humans. It needed time, so they needed to hold it in place. But that would result in Tamayo dying, so Ai hoped to help.

She used her blood and cursed it, and then it was mixed in with medicine. They had to try it on a Demon, but her blood was like poison to that of other Demons. She was a Pseudo Progenitor, and her blood was almost at the same level as Muzan, and with the Curse, it was even more harmful.

Then, why was it that Tamayo had to die? It wasn't enough because her blood would spread through his whole body. She might be close to it and even be able to fight his blood with the curse, but her control over it wasn’t enough.

To fight it, she would have to give the thought of fighting and focus only on him. Or, they could put a portion of her blood in him. Through spikes, and destroy his whole body, forcing him to regenerate, and her blood would piggyback on that, spreading through his entire body without being activated. Her blood, mixed with medicine that would turn him back into a human, and then her sealing slowed down his regeneration powers to allow her blood to mix in well.

Muzan was far weaker than his prime, and the Hashira still felt a threat of death when they saw him standing on top of broken hands. His hair had grown longer, white, and there were numerous mouths over his body with sharp fangs with dark-red massing growing from the end of each limb, branching into his body. But more than that, there was a third eye on his forehead, a scarlet one, “I don’t know what you did…whose blood you put inside me…but it has failed to kill me. Not only that…it has made me stronger.”

“We’ll see about that,” Rengoku got hold of the katana, and others followed his lead.

“Grand Flame Breathing!”

“Love Breathing!”

“Serpent Breathing.”

““Flower Breathing.””

“Grand Wind Breathing.”

“Blood Demon Art!”

“Grand Stone Breathing.”

“Grand Water Breathing.”

“Grand Mist Breathing.”

“Grand Insect Breathing.”

“Grand Thunder Breathing.”

“Beast Breathing!”

“SUN BREATHING!!”

Muzan’s third eye moved, and his limbs stretched out, becoming whips of flesh that managed that attack every Hashira at that moment.

They all moved away to change their angles and attack. Only, the tentacles moved, stopping them by wrapping around their swords at precise, weak points of every move at once, stopping every last one of them from attacking.

“I never saw the world as clearly as I am seeing it now,” Muzan’s third eye watched them one by one, stopping at Tanjiro, “You…I thought I destroyed everyone who ever knew about Sun Breathing. To think that man…knew I would do that and left behind a seed.”

Muzan stepped forward, and more limbs grew out of the whips of flesh, attacking their stomach, chest, thighs, hands, neck, every injury that they had sustained during the fights till now, “I’ll agree…that even though he was but a human…he managed to reach a realm above me. Now…I have surpassed even him. All that is left is to kill Every Demon Slayer and absorb that girl for her blood.”

Rengoku coughed out blood, “Grand Flame Breathing!!!”

“You don’t learn,” Muzan’s limbs pierced through his lungs, yet he continued, “Purgatory’s End!!!”

He dashed forward, much to everyone’s shock; the whip tore his lungs and internals apart, yet he reached Muzan, slamming down the katana, cutting apart every limb that came out of Muzan, and yet when the blade was about to cut his chest apart.

“You do not understand….” Muzan stopped the blade with the tip of his finger, pushing it back, “I am no longer a Demon. I am on the verge of becoming something much more. A Demon God.”

“Not while we are alive!!” Tanjiro appeared beside him, raising his sword, thrusting forward, covered in fire, “Sun Breathing! Sun Flower Thrust!!!”

“He said right!!!” Sanemi watched as Gyomei pulled Rengoku away, “Grand Wind Breathing!!! Rasengan!!”

He rotated 360 degrees in the air, and a Rasengan formed around him that fell on Muzan.

The Demon wanted to stop it, but his limbs had been cut, and he was caught off guard by the Sun Breathing again, let alone this move which fell on his body, twisting it from inside out. He wondered why he couldn’t stop it when his third eye saw through the twisting wind, seemingly infinite blade, and the Demon Mark on his face, ‘That mark!!!!’

Obanai Iguro didn’t go towards Rengoku. Instead, he had started preparing a move to deal a death blow, “Grand Serpent Breathing! First Form! Formation of Thousand Snakes!”

This move depended on how many swings he got to make. If he had more time, he could do up to ten thousand of them, but right now, this was enough.

Tens of swords of visages of snakes, created from the pure force, tore the ground apart, rushing to Muzan, who was still regenerating. Though he got this new eye, his regeneration had slowed down.

While he was regenerating from the damage, the snakes started to attack it, but the eye helped him see the future, help him weave the path, and dodge more than nine hundred of them.

Muzan didn’t even have to look up, the eye allowed him to see through their attacks, and he knew thousands of bloodthirsty water sharks were coming down towards him, creating a wave that was meant to destroy him.

“A thousand Thorns,” Muzan raised his right hand, his fingers stretched, and they branched out into thousand spikes that poked every last one of the water sharp, destroying the move before it even reached him. Though much of the water did fall on him, giving them another chance to attack.

“Sixth Form! Cat-Legged Winds of Love!!”

“Flower Breathing!! Final Form! Equinoctial Vermillion Eyes!”

“YOU PESTS!!” Muzan shouted, and nine strong whips came out through his body, slashing the two backward, injuring them in one go.

Before his attacks, the temporary ones were strong, but this was on a different level. This one gorged the land around him, breaking them as shockwaves hit everyone else who was moving to attack him.

He gasped for breathing; focusing on his regeneration made him use less power of this eye, and the eye made his regeneration slower. He had thought he succeeded, but now it seemed he hadn’t.

“That girl!! Her blood!” He rose in the air with the help of his whips, ordering, “Nakime!”

The door in front of him opened, but he didn’t find Ai, who was injured; he found Ai standing calmly on her face.

The look on her face made his footsteps stop, “There is something different about you.”

Ai gently nodded, opening her eyes, “It’s time to say goodbyes…so I took a moment.”

For a moment, she froze, fixing her eyes on the third eye that Muzan fashioned, and she gripped the hilt of her sword, “You know…Muzan. I pity demons…and I love them…or hate them. But you…you were one that I felt nothing about.”

She dazedly looked at that eye, “That eye…belongs to my father. You have no right to it.”

Before, she didn’t kill the Demon that controlled this Castle because they hadn’t reached this point of the plan, but now, there was no need.

“You! You are not human,” Muzan was stunned as if meeting Ai for the first time. He could tell now that she wasn’t human. Maybe only one-fourth of her was human; there was blood in her, different from his own. It was as if she was the First Demon, too…No. She wasn’t the first.

“True Wood Breathing: Zenith Form – Calamity from The Sky.”

He knew she had completed the move when she placed her palm on the sword, but nothing came towards him. He threw all eight whips towards her, but they were stopped by the Hashira, who came after one after another. When wood came from the ground, wrapping around them, stopping them in place to stop those whips.

But not only them, more of those sealed Muzan inside them, giving them time to talk.

“I wanted to say proper goodbyes…maybe stay a few days longer. But ever since I woke up…I knew I’d soon have to say goodbye,” Ai gently smiled at them, “Rengoku…Tanjiro…Zenitsu…Inosuke. It was fun traveling with you guys…I came to love those days. Thank you for all the wonderful memories that you helped me make.”

“Ai….”

“Miss Ai….”

*Sob*Sob*

“Don’t!! Mentions it!!!”

“Sir Gyomei…thank you for teaching me.”

Gyomei cried, nodding without saying anything.

“Sanemi, Genya. The two of you make sure to get along,” Ai grinned.

“Shut up!!”

“Yes!”

Ai breathed in, “Muichiro…I would have loved to hear more about your brother. Remember him…your parents…and if possible…remember…Michikatsu Tsuchiguni, and Yoriichi Tsuchiguni.”

Muichiro wasn’t sure why she would ask him this, but knowing what it represented, he nodded.

“Mitsuri!” Ai raised her spirits, grinning at the girl, “I know you were always worried about your strength, but I’d say…Iguro loves you with all his heart. Marry him!”

“It’s none of your business,” Obanai Iguro shot a look towards her, and then his eyes met with crying Mitsuri as his gaze softened.

“And! I loved bird watching with you,” Ai winked at Mitsuri, who became blushing red and started crying, “Ai! I’ll miss you….”

“You better,” Ai chuckled, turning her eyes towards Giyu.

“Giyu….”

“Hm?”

“Sabito and Makomo asked me to tell you….”

Giyu’s eyes widened, hearing the names he thought he wouldn’t hear again, “You are the only Water Hashira they accept. So be proud and live! Because they are always watching you!”

Giyu couldn’t move; the only thing he could do was let his head slump as his shoulder shook.

“Shinobu.”

“Ai.”

Ai smiled, “I always thought…if I had a sister, then it’d be like you. You…made me feel right at home…always. Thank you for that.”

Shinobu closed her eyes as a tear slipped past her cheek, “Don’t…please…. I don’t want to lose another sister….”

“Then from now on…live and protect everyone,” Ai softly smiled, using the Life Breathing Form to destroy poison from her body.

At the same time, all of them felt life energy pour into them, increasing their life force and countering the negative effect of the Demon Mark.

“Tsuyuri….”

“You promised….”

“Tsuyuri…for me…live. Live with joy, fall in love, have a family, laugh when you want, cry when you want. Please! Live a happy life…because nothing would make me happier!”

“YOU PROMISED!!”

“I lied,” Ai bit her lip, sniffling, “I am sorry…I lied.”

She breathed in, wiping her tears as cracks started to appear in the tree that sealed Muzan.

“It’s time,” The moment Ai declared that the Infinity Castle was blown apart. Its walls were obliterated, the Demon that controlled it was destroyed, the night sky above them shined, and the signs of upcoming dawn were on them.

But more than that, what shocked them to the core was the green aurora in the sky, and a massive wooden hand, holding a broadsword, coming down from the sky. It transversed the space and destroyed Infinity Castle when the tip of that sword touched it.

Muzan broke apart the tree, coming out, “Ai Senju!!!”

“I wasn’t lying when I said I didn’t want to say goodbye so soon…but …you used my father’s eye,” Ai raised her chin, “That pissses me off. But before I deal with you….”

She shook her head, grinning at everyone else, “Live…for me. Live well.”

“True Wood Breathing: Zeroth Form. Sealing Hashira.”

“Heh…you still love doing that….” Rengoku laughed as wood blocks rose from the ground, different from wooden roots; they rose like a building, covering everything around the Hashira’s.

“I know!! You will live Ai!!!”

“Goodbye…Kyojuro…Rengoku. I left letters for everyone.”

The wood block covered Rengoku’s grinning face and everyone else’s, forming defensive pillars that reached the sky.

Abruptly, she coughed out blood, looking down at the massive spike formed by the swirling nine whips that created a hole in her chest.

She raised her eyes to look into Muzan’s and shook her head, “It’s too late. Muzan. It’s over.”

“It’s not!! I am still alive!! I won’t die!!”

“You were dead…the moment I summoned that thing from space,” As she said, the tip of the sword touched the ground, and the force of the blast covered the mountain range they landed on.

The forests she had created inside the Infinity Castle took most of the blast to stop it from destroying the whole of Japan as the forest grew, keeping it contained to the mountain range, barely succeeding.

Everything in the forest, be it Muzan or Ai, was seemingly destroyed down to its last cell.

Meeting at Crossroads,

Ai opened her eyes, finding Yoriichi standing in front of her, with a smile on his lips.

“Thank you.”

Ai shook her head.

“Now that you have done everything you wanted to do …let me teach you everything I learned throughout my life before I send you off.”

Ai raised her broadsword, dividing it into two, pointing at Yoriichi, taking her stance, “I’d love to learn.”

{And that is the end of the volume 1!!}

{At first I was confused where to start the My Hero Academia Volume, and what role would Ai play in that world, teacher, student, hero...even villian? Neutral maybe. Well. I finally figured it out, and wrote starting few chapters, ones that I am satisfied with. I wasn't expecting that really. Anyway, next week I will release those chapters all together, or you could find them on my Patre-on in about 12 hours!}