In a world caught between the fading traditions of old Japan and the glittering allure of the burgeoning Meiji era, a poignant tale of love, betrayal, and bitter revenge unfolds. At its heart are 間貫一 (Hazama Kanichi), a diligent and earnest student, and 鴫沢宮 (Shigisawa Miya), a woman of striking beauty, whose pure affection for each other seemed destined for a lifetime of happiness. They were betrothed, their future together a subject of envy among their peers.
Their innocent world begins to fracture at a festive New Year's karuta gathering. There, a wealthy banker's son, 富山唯継 (Tomiyama Tadatsugu), enters the scene, his fingers adorned with a massive diamond ring that glints with the promise of prosperity. Miya, though betrothed, finds herself drawn to this opulent display, and her parents, swayed by the prospect of immense wealth, readily encourage Tomiyama's suit. Miya's heart, once solely devoted to Kanichi, begins to waver, seduced by the glitter of gold and the comfort it promised.
The inevitable betrayal culminates in a dramatic confrontation on the shores of Atami. Kanichi, heartbroken and enraged by Miya's decision to abandon him for Tomiyama, confronts her. In a moment of raw despair and fury, he curses her, famously declaring, "Remember this, Miya. On the seventeenth of January, this moon shall surely be clouded by my tears. When the moon clouds, know that Kanichi, somewhere, is weeping and hating you as he is tonight.". With those words, he cruelly kicks her away, severing their bond with a violence that scars them both forever.
From that fateful night, Kanichi's path veers sharply into darkness. Abandoning his studies and any hope of a conventional life, he transforms himself into a merciless moneylender, a "Golden Demon" (金色夜叉). His once gentle spirit hardens into a cold, calculating resolve, fueled by an insatiable thirst for revenge against Miya and the world that values wealth over love. He becomes a master of his cruel trade, amassing a fortune, yet living like a ghost, cutting ties with friends and rejecting any affection, including that of the persistent Mitsue.
Meanwhile, Miya's life as Mrs. Tomiyama, though outwardly lavish, is a gilded cage. Despite the riches surrounding her, her heart remains hollow, haunted by the memory of Kanichi and the love she cast aside. Guilt and regret gnaw at her, leaving her in a constant state of melancholy. She writes numerous letters to Kanichi, begging for his forgiveness and a chance at reconciliation, but he, still consumed by his bitter hatred, burns them unopened.
Years pass, and their paths inevitably cross again. Kanichi, now a formidable and feared figure in the world of finance, finds his business dealings bringing him into contact with Tomiyama and his associates, further intertwining his fate with Miya's. Miya, desperate, finally seeks him out in person, pleading for absolution. Yet, Kanichi's icy demeanor remains impenetrable, his words sharp as daggers. In a harrowing scene, driven to the brink by his coldness and the provocations of Mitsue, Miya attempts to take her own life with a short sword, crying out for his forgiveness.
The story, however, remains tragically unfinished, a testament to the author's untimely death. It concludes with Miya collapsing, her fate hanging in the balance, and Kanichi grappling with the profound impact of her desperate act. His heart, long encased in ice, shows a flicker of turmoil, hinting at a possible shift from his unwavering vendetta. The ultimate resolution of their tragic love story, the triumph of love or gold, is left to the reader's imagination, a poignant echo of the unresolved struggles within the human heart itself.