In 1536, he celebrated his attainment of manhood, and was honored to have henki (granting subordinates the use of a character from the superior's real name), receiving a character "晴" from the twelfth shogun, 足利義晴 (Yoshiharu ASHIKAGA), and changed his name to `晴信' (Harunobu) (according to Kohakusaiki (a record and diary on the history of the Sengoku period supposedly written by Masatake Komai), `信' is tsuji (a distinctive character used in the names of all people belonging to a single clan or lineage) of the Takeda clan).
天文5年（1536年）に元服し、室町幕府第12代将軍・足利義晴から「晴」の偏諱を賜り、「晴信」と改める（『高白斎記』による、「信」は武田氏の通字）。