Suzune Hizuki, bound by a ceremonial pact between the Hizuki and Rindou families, was destined to fulfill a ritual requiring a union of the two bloodlines every three generations during the Hinotsukisai. Designated as Naoto Rindou’s fiancée, her engagement earned reluctant approval from her eldest sister, Shino, who acknowledged Naoto’s sincere feelings for Suzune. While the match satisfied the ritual’s immediate requirements, Shino harbored silent resistance toward the Rindou family’s deeper ambitions.

Suzune’s path diverged abruptly when a fatal car accident claimed her life, with Masakazu—Yuiko Hizuki’s husband—behind the wheel. Her untimely death left the ritual incomplete, compelling Naoto to name her sister Ayumi as successor. Shino concealed her dissent, prioritizing Ayumi’s fragile resolve over her own misgivings.

The tragedy’s aftermath exposed fractures within the Hizuki household, juxtaposing devotion to ancestral rites against the weight of personal bonds. Suzune’s absence became a silent force, propelling conflicts over legacy, sacrifice, and the invisible scars etched by centuries of tradition.