Aizo was born in a farmer's family in Shirogane Village, Azumi County, Nagano Prefecture (later, Hotaka-cho Town, currently Azumino City) in 1870, and dropped out Matsumoto Fukashi High School, Nagano Prefecture at the 3rd grade, and enrolled in Tokyo Senmon Gakko (the predecessor of Waseda University).
愛蔵は、明治3年長野県安曇郡白金村（後に穂高町、現安曇野市）の農家に生まれ、長野県松本深志高等学校を3年で退学し、東京専門学校（早稲田大学の前身）に入学した。