The Hyakki Gokoku is a hyper-stylized, ornate katana with a blade that subtly glows with a faint blue luminescence, symbolizing its mystical origins. The hilt is wrapped in dark, weathered leather, contrasting with the polished, mirror-like finish of the blade, which features intricate engravings of mythical creatures along its length. The guard is a complex, asymmetrical design resembling swirling flames, crafted from a dark, metallic alloy with a matte finish to emphasize its detailed craftsmanship.