Hakkenden: Eight Dogs of the East opens in the village of Ootsuka, where Shino Inuzuka, Sousuke Inukawa, and Hamaji survive a fire set after the settlement is wrongly believed to have been wiped out by a virus. As the flames close in and death seems certain, a strange man carrying a sword tells them they must choose if they want to live, and that night changes everything for the three children. Five years later, the family of three lives under the watchful eye of a small Imperial Church in a nearby village, trying to preserve a fragile peace. Shino now carries the soul of the demonic sword Murasame, Sousuke can transform into a dog, and both young men bear the same peony-shaped birthmark.
That calm ends when the Imperial Church moves to reclaim Murasame and kidnaps Hamaji to draw Shino and Sousuke into the open. Forced to confront the past and put their differences aside, they head for the Imperial Capital to rescue the girl they love as a sister, only to find themselves pulled into a wider struggle. Along the way they encounter other marked warriors, including Genpachi Inukai and Kobungo Inuta, and become tied to eight mystical gems and their scattered owners, with figures such as Riou Satomi drawn into the same conflict. The series builds its supernatural drama around loyalty, danger, and the burden of Murasame as the fate of the Eight Dogs gradually comes into view.
