Genichiro Tazaki is the landlord of Chikusei-sou dormitory and the official coach for the Kansei University track team, though he largely delegates daily management and coaching duties to Haiji Kiyose, relying on Haiji's drive. He presents as an elderly man with thick eyebrows and a beard on his chin, consistently wearing a distinctive red hat.

His name, "Genichirō", uses the characters for "source" (源), "one" (一), and "son" (郎), while "Tazaki" combines "field" (田) and "cape" (崎). He carries a notable past reputation as a former elite athlete once called "the treasure of the Japan Association of Athletics," contrasting with his present hands-off approach. He owns a dog named Nira, who is sometimes seen with him. His role provides institutional support as dormitory owner and nominal team coach.