Toyo was the younger son of Sumitomo Koji, master of the Doi No Fugu, and the second male. In his youth, he was very close to his older brother, Sumitomo Yoichi, who was always fascinated by stories of travelers, and his younger sister Sumitomo Skoshi.
When as tradition dictated Yoichi was sent outside Maeshi Province for training as a chef, Toyo and Skoshi knew he would never come back. He didn't, and Toyo became the heir. With the turmoil in the province between the Michimori clan and the Korimori clan, he undertook his training at home. In 1359 arrived at the inn the ronin Haka Kinnori that after a talk with their father Sumitomo Koji started t live with them. Soon Toyo and Skoshi befriend Haka that also teach them karate