Asakichi Iwaya is a retired professor living in Tokyo during the 1964 Summer Olympics, residing with his family as grandfather to Toshirou. He presents as a fit elderly man with light-colored hair, a short beard, and requires corrective glasses.

His life takes an unexpected turn when he discovers Demetrios, an ancient Greek vase painter displaced by a lightning strike, and provides the bewildered time traveler shelter. Asakichi and his family accommodate Demetrios, assuming him a harmless foreigner. Though initially baffled by Demetrios's sudden appearances and disappearances, Asakichi adapts swiftly to these strange events.

He becomes Demetrios's guide through 20th-century Tokyo, facilitating his exposure to the modern world, including the Olympics. Asakichi leverages his academic background to help Demetrios understand unfamiliar situations and navigate problems stemming from their vast cultural and temporal gap. His assistance extends beyond orientation; he actively supports Demetrios in gathering information on modern sports and events. This knowledge proves crucial for Demetrios's later efforts to organize athletic competitions in ancient Greece.

Throughout Demetrios's unpredictable time-travel episodes, Asakichi remains a consistently supportive, adaptable, and grounding presence.