A decade after the intense Holy War in Hong Kong, Mochizuki Jirou, known as the Silver Blade for his valor in defeating the Kowloon Children despite personal tragedy, returns to Japan alongside his younger sibling, Mochizuki Kotarou. Upon their arrival, they unravel a sinister plot orchestrated by surviving Kowloon Children attempting to breach the impenetrable 'Special Zone,' a bustling metropolis shielded by an invisible barrier barring their entry without invitation. Here, humans are Red Bloods, vampires are Black Bloods, and the Mochizuki Brothers belong to the rare Old Blood lineage, the esteemed descendants of a noble vampire clan. As Kotarou falls prey to the enemy's clutches, Jirou is compelled to wield his blade once more in a relentless battle for his brother's rescue and the city's safety.