Rain. Poison. Explosives. Vengeance. It's a deadly combination that forms a volatile mixture of deceit, betrayal, and hate as the final showdown between Lone Wolf assassin Ogami Itto and his nemesis Retsudo begins. While the torrential rains continue to pound Edo, the fiery Retsudo and his bloodthirsty Yagyu army rush along the banks of the swelling Hatcho River, racing to beat a load of explosives that's traveling down the other side, heading right into the hands of the vengeful samurai Ogami. Meanwhile, the cunning poisoner Abeno sees his chance to destroy both sides as they run headlong on their collision course — he's going flood all of Edo! Forced to put their battle aside, Ogami and Retsudo find themselves fighting side by side to save all of Edo from the floods, while Ogami's little son Daigoro wanders alone, fighting for his life and searching for his father! It's a deluge of evil, and it threatens to wash away all that stands in its path!