According to the 'History of the Satake family', Yoshinao fell asleep during seeing sarugaku (form of theater popular in Japan during the 11th to 14th centuries) and provoked his foster father Yoshinobu.
「佐竹家譜」によれば、江戸城における猿楽の見物中に居眠りをしてしまい、養父義宣の怒りをかったためという。