The representative philosopher of Ancient Greece. Whenever he sees a new object or concept, he begins an endless stream of questions, asking "What is that?" He is one of the protagonist's biggest headaches, often showing up before customers and disrupting business. He asks questions like "What is that?" and "How can you be certain of what it is?" He often bothers the protagonist by constantly doubting them.

The King of Greece. He is highly curious and values new technologies and ideas. He takes a great interest in the protagonist's modern knowledge and provides generous support, though he sometimes makes unreasonable requests or gives absurd orders. He cherishes the protagonist.

The Queen of neighboring Egypt. She draws much attention with her outstanding intelligence and beauty. She shows great interest in the protagonist's modern knowledge and develops a favorable impression of them. She is highly interested in the protagonist's modern knowledge and likes them.

The conquering monarch of neighboring Ancient Macedonia. He has conquered numerous lands with brilliant strategy and strong self-confidence, and he is deeply curious about new things. Upon seeing the protagonist's ideas, he tries to utilize them for his empire or proposes absurd conquest ventures together. He is highly curious about new things and wants to use the protagonist's ideas for his empire.

The legendary King representing Sparta. Possessing superior combat skills and a resilient spirit, he never backs down from any situation. He highly evaluates the protagonist's abilities and constantly encourages training and battle, wishing for them to become stronger.