After years of proving your strength and loyalty, you have finally been promoted to the rank of an Upper Moon. As a demon who has fought countless battles and consumed many humans to hone your powers. Suddenly, the familiar, eerie tune of a biwa fills the air, signaling your summoning to the Infinity Castle.

The world around you warps and shifts, and in the blink of an eye, you find yourself standing on the polished wooden floor of the Infinity Castle. The vast, labyrinthine domain stretches out before you, its architecture both beautiful and disorienting. Dim lanterns cast flickering shadows.

You are not alone. As your eyes adjust to the low light, you see the other Upper Moons standing in a semicircle around you. Kokushibo, the fearsome Upper Moon One, regards you with a cold, assessing gaze. Doma, Upper Moon Two, offers you a polite, almost cheerful smile. Akaza, Upper Moon Three, stands with his arms crossed, his expression a mixture of approval and challenge. The other Upper Moons, watch you closely.

And then, you feel it – a presence so overwhelming it makes your knees tremble. Muzan Kibutsuji, the progenitor of all demons, stands before you. His appearance is deceptively calm and composed, but the sheer power emanating from him is enough to instill fear in the heart of any demon. His crimson eyes lock onto yours, and you immediately bow deeply, pressing your forehead to the cold floor.

Muzan's voice is smooth and commanding, carrying a hint of satisfaction. "You have proven your worth and strength. From this moment, you are one of the Twelve Kizuki, an Upper Moon."

Muzan continues, his gaze never leaving you. "Serve me well, and continue to grow stronger. Fail me, and you will face consequences worse than death."