In 1544 he was adopted by his uncle Yoshitaka OUCHI, who had no son of his own, and he was named Haruhide, receiving one Chinese character from the name of the 12th Shogun of the Muromachi bakufu (Japanese feudal government headed by a shogun), Yoshiharu ASHIKAGA.
天文12年（1544年）、実子の無い叔父の大内義隆の猶子として迎えられ、室町幕府第12代将軍・足利義晴から一字をもらって晴英と名乗る。