Several months had passed since the battle on the Mugen Train.
That desperate battle before dawn, and its unbelievable conclusion, had been like a boulder cast into a lake, sending ripples through the Demon Slayer Corps that lingered long afterward.
Upper Rank Three had fled with an arm severed.
The Flame Hashira, Kyojuro Rengoku, had miraculously survived.
The newly appointed Thunder Hashira, Uesugi Sasuke, had used a pair of demonic eyes capable of unleashing undying black flames to forcibly rewrite the fate of what should have been certain death.
These tidings had long since become legends among the Corps members.
And one of the men behind those legends, Uesugi Sasuke, was now sitting cross-legged on the roof of the Butterfly Mansion, resting with his eyes closed. His Thunder Hashira haori stirred gently in the wind, and he seemed like a peerless blade with all its sharpness sheathed, blending into the tranquility around him.
His injuries had long since healed, but the increase in ocular power brought about by awakening his Mangekyō Sharingan, as well as the newly unlocked "Susanoo," required considerable time to adapt to and master.
In the courtyard, Tanjiro, Zenitsu, and Inosuke were undergoing rehabilitation training.
After this period of grueling practice, Tanjiro could now skillfully maintain "Total Concentration: Constant," and his breathing had become sustained and resilient. Inosuke was as energetic as ever, swinging two brand-new Nichirin Blades and roaring like a wild beast.
Only Zenitsu was still dodging Aoi Kanzaki's pursuit while wailing that the medicine was too bitter and the training too exhausting.
It was a peaceful scene filled with noise and vitality.
Yet that tranquility was destined to be utterly shattered by a "flashy" man.
"Hey, hey, hey! Give me a few female Corps members! I'm taking them on a mission!"
An utterly arrogant