"Nobunaga the Fool" is a 24-episode anime series that blends historical figures, science fiction, and fantasy elements into a unique narrative. The story unfolds across two distinct worlds: the Western Star, a technologically advanced civilization, and the Eastern Star, a land steeped in mysticism and feudal traditions. The Western Star, led by figures like Leonardo da Vinci and Jeanne Kaguya d'Arc, faces imminent destruction due to the collapse of their planet. In contrast, the Eastern Star, ruled by warlords and samurai, remains embroiled in constant conflict.

The central figure is Oda Nobunaga, a young and ambitious warlord from the Eastern Star, who is prophesied to become the "Savior King" destined to unite the two worlds. Nobunaga is portrayed as a charismatic yet unconventional leader, often challenging the status quo. His journey begins when he encounters Jeanne Kaguya d'Arc, a warrior from the Western Star, who arrives on the Eastern Star seeking the prophesied king. Jeanne believes Nobunaga is the key to saving both worlds and becomes his ally, guiding him toward his destiny.

The narrative explores Nobunaga's rise to power as he gathers allies and confronts rival warlords, including his own brother, Oda Nobukatsu, and other historical figures reimagined in this alternate universe. Mitsuhide Akechi, a cunning strategist and Nobunaga's childhood friend, plays a pivotal role, often oscillating between loyalty and betrayal. The series also introduces other notable characters, such as Caesar, Alexander, and Himiko, who represent various factions and ideologies.

As the story progresses, the conflict between the Western and Eastern Stars intensifies. The Western Star's advanced technology, including giant mechs known as "Regalia," clashes with the Eastern Star's reliance on spiritual energy and traditional warfare. Nobunaga's quest to unite the worlds is further complicated by internal strife, political intrigue, and the revelation of ancient prophecies tied to the "Holy Grail," a powerful artifact capable of reshaping reality.

The series culminates in a climactic battle that tests Nobunaga's resolve and leadership. His vision of a unified world faces opposition from those who seek to maintain the divide between the two stars. Through alliances, betrayals, and personal growth, Nobunaga strives to fulfill his destiny as the Savior King, ultimately challenging the very fabric of the worlds he seeks to unite. The narrative weaves together themes of ambition, destiny, and the clash between tradition and progress, creating a complex and engaging story.