Shunichirou Sakaki hailed from Jouga-machi, a 1950s-era town famed for its hassaku orchards and whispered legends of kamibito—wolf-like beings with heightened senses vulnerable to pheromones from rare "Temptations." Born a Temptation, his presence provoked violent obsession in kamibito, a peril he defied by engaging in a forbidden romance with Mieko, a kamibito woman. Their union breached ancient laws, culminating in Mieko’s assassination by Nemuru Kushinada, the town’s enforcer.

Devastated by authorities’ apathy toward her death, Sakaki spent two years orchestrating vengeance. Convinced Jouga’s kamibito and complicit citizens perpetuated systemic violence, he infiltrated their ranks in the anime as a hitman targeting Hiroshi Kuzumi, a fellow Temptation. After abducting Hiroshi to bait Nemuru into a fatal confrontation—a plan foiled by her restraint—he unleashed a feral kamibito during the Hassaku Festival to expose the town’s secrets.

His vengeance climaxed with flooding Jouga via dam rupture, partially destroying it before intervention. Rejecting Nemuru’s plea for self-sacrifice, he clashed with former ally Kaori Mana, their struggle ending in a fatal plunge. The visual novel diverged: he bombed the town or manipulated humans to eradicate kamibito, succeeding in certain routes. Deeper lore revealed childhood trauma—orphaned early, raised by a cruel uncle—forging his ruthless ethos.

Across adaptations, Sakaki’s crusade blended personal vendetta with twisted justice, targeting Jouga’s corruption through calculated schemes. His manipulation of Hiroshi and Nemuru underscored tactical brilliance and uncompromising resolve, framing him as a figure warped by loss and systemic brutality. The narrative wove his actions into a cycle of violence, illustrating the cost of oppression through his downfall—a strategist consumed by the very cycle he sought to shatter.