To end the curse that had plagued his family for millennia, he chose the darkest path.

As the 97th Master of the Demon Slayer Corps, Kagaya Ubuyashiki has always been a gentle and revered leader in the hearts of all his members. However, as the curse increasingly erodes his life, and as he foresees that his daughters will repeat the same mistakes, on the verge of despair, he makes a choice that will shake the world—to make a deal with Muzan Kibutsuji and become the most hidden Upper Moon Zero.

By day, he remains the lord who guides everyone in the fight against demons; by night, however, he is loyal to his millennia-old nemesis. When the truth is revealed on the eve of the final battle, the Demon Slayer Corps' faith crumbles overnight. The former "father" becomes the most despicable traitor, and the Pillars who once swore their undying loyalty turn their blades against each other.

But at the end of this sin-soaked road, does Kagaya hold a trump card that can turn the tide for a thousand years? When wisteria blossoms alongside bloodshed, this game of chess that began with betrayal will finally reach a shocking conclusion.

Once the gears of fate begin to turn, love and hate intertwine into an impenetrable net. Turning to Ashoka's "The One I Loved Most Was the Murderer," the male and female protagonists embark on a perilous and fraught journey to uncover the truth behind the unexpected death of the male protagonist's wife.

COVID-19, disease, hardship, misfortune, workplace struggles, love and hate, life and death… They persevered through countless difficulties, and they embraced new life amidst despair. This book celebrates the steadfastness and devotion of love, showcases the resilience and brilliance of humanity, and takes you deep into the labyrinth of human nature to explore the true meaning of love and redemption.

In this battle between love and sin, can they uncover the truth? The book features both thrilling mystery and delicate, moving emotions; it depicts a love story that transcends life and death, and also reveals the ugliness and justice of the world.