The world has already fallen to the oni before you meet the people trying to take it back. Musashi and Kojiro aren't heroes destined to save anyone, they're kids who picked up cursed swords and decided to fight anyway, knowing the odds are mathematically impossible. You watch them build something real with Tsugumi, three people learning to move together while everything around them proves the fight was over before it started.

Musashi and his ragtag band of swordsmen have claimed their Kitetsu Blades, the only weapons capable of piercing oni flesh. After Musashi saves the shy princess Michiru Saruwatari from a demon, Kojiro learns that his father belonged to the Uesugi clan. Eager to uncover his past, he and the Kanemaki Bushi join Uesugi Tatsuomi's campaign against Yamata no Orochi, an eight-headed dragon Kishin that threatens to swallow Awaji Island. The journey forces unlikely alliances as Musashi's crew encounters other bushi groups, each with their own agendas. Uesugi Tatsuomi commands a massive force gathered to slay a demon god no one has ever wounded. Humbled by his weakness and poor teamwork, Musashi must learn to fight alongside his new allies, while the Obsidian Eight resume their hunt for the goddess who dwells within him. Humor cuts through the tension in this action fantasy adventure.