Multiverse Shenanigans: Raja's Journey

After that fateful meeting with Oyakata-sama, the leader of the Demon Slayer Corps, I was given everything I needed to start my work: herbs, medical equipment, and a team of attendants. The resources were abundant, but I had insisted on paying for everything myself, producing a hefty gold bar as payment. When Oyakata-sama tried to refuse, I shook my head.

"I have no right to accept your money for a treatment that cannot cure your condition," I said firmly. "This is my mission, my purpose."

He had smiled gently, understanding the pride that came with my profession. "Then I will not argue."

I spent the next year deep in my work, testing and experimenting, with my mind running at a steady 25% capacity—though Maya swore I could push it further if I really needed to. The work was grueling. The virus, as I soon discovered, wasn't just persistent—it was actively resisting my efforts. It was as though it could sense that something was wrong, accelerating its spread the more I tried to interfere.

But I was determined. I spent long nights running simulations, using trial and error to mix various herbs and chemicals. In the end, I designed a six-course vaccine that would halt the spread of the virus within Oyakata-sama's body. The treatment, however, was far from perfect. Each dose had to be administered every four hours over a 24-hour period, and the side effects were brutal—immense pain caused by the rioting virus inside his body. I estimated that if I had another three months, I could reduce the pain. But time was against us.

Maya's voice echoed in my head as I went over my research. "According to the timeline, Oyakata-sama should be having children right about now. Your treatment is delaying that."

I frowned. "That's a problem. His lineage needs to continue. I have to act quickly."

In the midst of my intense focus, I met **Gyomei Himejima**, the Stone Hashira, a man whose physical strength was matched only by his kindness. Despite his towering frame and muscular build, he had the gentlest heart of anyone I'd ever met. When he told me his story—how he had lost the children he cared for and become a Demon Slayer to protect others—I couldn't stop the tears from welling up.

I hugged him tightly, burying my face in his chest. "Big bro," I sniffled, "I promise I'll do everything I can to help Oyakata-sama."

Gyomei's large, warm hands gently lifted me up, placing me on his broad shoulders like I was a child—which, I suppose, technically I was. "Please," he said, his deep voice filled with sincerity, "help our leader. I wish to see him free from his pain."

I grinned through my tears, making a grand declaration. "I'm the man who will become the king of medicine!" My voice echoed through the halls, causing some of the attendants to stop and stare.

---

Exactly one year after I began my research, the day of the treatment arrived. Oyakata-sama was prepared for what would be the most excruciating 24 hours of his life. He sat in the center of a room, surrounded by soft pillows and tightly bound with cushions and restraints to prevent him from injuring himself during the ordeal. Gyomei stood by his side, a pillar of strength, while his wife prayed quietly in the corner, whispering to Daikokuten for mercy.

I stood at Oyakata-sama's side, holding the first syringe in my hand. The vaccine glimmered in the morning light, the culmination of a year's worth of work.

"Are you ready?" I asked softly.

Oyakata-sama smiled, his eyes filled with determination. "I have the will of my ancestors. I will bear this pain."

With a nod, I injected the first dose at 6 A.M. The effect was immediate. Oyakata-sama's body convulsed, and he screamed—a bloodcurdling sound that echoed throughout the mansion. His muscles spasmed violently, and I could hear the crackling of joints as his body fought against the virus. His attendants ran from the room in terror, unable to bear the sight of their leader in such agony.

Only his wife, Gyomei, and I remained.

After an hour of this torment, I injected him with fluids to keep him hydrated and provide energy. His fever spiked, and he continued to thrash, but the pain gradually lessened. I administered treatments to prevent him from suffering a stroke or any lasting damage, constantly monitoring his vitals.

Oyakata-sama's wife knelt beside him, tears in her eyes, her lips moving in silent prayer. Gyomei stood like a stone guardian, his hands clasped in front of him as he too prayed for the leader's endurance.

The process continued every four hours, with Oyakata-sama receiving another dose of the vaccine. Each time, the pain was unbearable, but he endured with remarkable strength. By the time the sixth and final dose was administered at 6 A.M. the next morning, his body was a battlefield of fever, sweat, and trembling muscles.

Exhausted, I collapsed into a chair, wiping the sweat from my brow. After taking a few moments to catch my breath, I drew a blood sample from Oyakata-sama and retreated to my lab. There, I spent the next 12 hours analyzing the results, running tests, and scribbling notes on my board.

When I emerged, I found Gyomei and Oyakata-sama sitting together. Despite everything he had endured, Oyakata-sama was sitting up, drinking a cup of juice to replenish his electrolytes. His wife stood beside him, relief washing over her features.

Gyomei's sharp senses picked up on my presence immediately. He turned to me, his face filled with hope. "What are the results?"

I grinned, my face lighting up with a smug expression. "I'm the man who will become the king of medicine!" I declared, my voice triumphant.

Gyomei's face broke into a rare smile, and he lifted me off the ground, spinning me around as if I were a toy. Oyakata-sama's wife wept openly, her tears a mix of joy and relief, while Oyakata-sama smiled softly, patting her back to comfort her.

Once the celebration had calmed down, I explained my findings. "The virus has formed a shell around itself, meaning it can't spread any further. It's essentially trapped in your bloodstream. It's still there, but it's not damaging your body anymore."

Oyakata-sama listened carefully, his face showing signs of exhaustion but also hope. "So... it cannot spread?"

I nodded. "That's right. It's not gone, but it's contained."

Over the next three months, I worked tirelessly to develop the remaining treatments. The second drug, which I crafted with precision, reduced the pain and discomfort caused by the virus. Oyakata-sama would have to take it daily, like chewing gum, but it would ensure he could live without constant agony. The third drug was designed to be taken before any spiritual or holy activities, ensuring that his body wouldn't relapse during moments of physical or emotional strain.

Nine months later, Oyakata-sama's wife became pregnant. I monitored her closely, and when the time came, she gave birth to twin girls. I immediately tested their blood, and to my immense relief, they were free of the virus.

Oyakata-sama's joy was boundless. He held his daughters close, tears in his eyes. He turned to me and asked, "What can I give you in return for this happiness you've brought to our family?"

I didn't hesitate. "Train me in the way of the sword and breathing techniques."

Oyakata-sama looked surprised. "Why would a healer seek such skills?"

With a determined expression, I replied, "A medicine practitioner's job is to kill the virus and cure the patient. I've only temporarily solved your problem. To fully cure you, I must eliminate the source of the virus—Muzan Kibutsuji himself. So grant me permission to learn the way of the sword."

Oyakata-sama stared at me for a long moment before nodding, a smile spreading across his face. "Very well. You will have your training."