In 1550, when he was 13 years old, he went through the Genpuku (Coming of Age) Ceremony and took the name Yoshinobu, receiving the 'Yoshi' as henki (where an emperor, shogun, or daimyo gave one character from their name to a subordinate or those who went through genpuku) from the Thirteenth Muromachi Shogun, Yoshiteru ASHIKAGA.
天文19年（1550年）に13歳で元服し、室町幕府第13代将軍・足利義輝より偏諱を受けて義信と名乗る。