In the first episode of Yu-Gi-Oh: Duel Monsters, what book is Seto Kaiba seen reading at Domino High School?

The answer is Thus Spoke Zarathustra. Seto Kaiba is seen reading this book in the first episode of Yu-Gi-Oh! Duel Monsters to depict his philosophical mindset and intellectual nature. The choice of this specific book is significant as Thus Spoke Zarathustra by Friedrich Nietzsche explores concepts like the will to power, the Übermensch, and the idea of creating one's morals, reflecting Kaiba's ambition, determination, and quest for personal growth and power as a duelist and businessman.