Born on March 10, 1536, as the eldest son of the 12th Muromachi shogun Ashikaga Yoshiharu. In 1546, at age 11, he became the 13th shogun upon his father's abdication, but real power lay with the kanrei Hosokawa Harumoto and later Miyoshi Nagayoshi, forcing Yoshiteru into repeated exile in Omi. Determined to restore shogunal authority, he studied swordsmanship under Tsukahara Bokuden and mastered the secret technique 'Hitotsu-no-Tachi' of the Shinto-ryu school. He also worked to mediate between daimyo, including brokering peace between Uesugi Kenshin and Takeda Shingen. On May 19, 1565, roughly 10,000 troops of the Miyoshi Triumvirate and Matsunaga Hisahide attacked his Nijo residence. Yoshiteru thrust his prized collected swords into tatami mats and fought on, switching blades as each was dulled, but was overwhelmed and killed. He was 30.

A shogun of both literary and martial talent who never abandoned his pride, even in an age of chaos. He took up the sword himself in his final stand and actively mediated disputes between daimyo, driven by a fierce will to restore the shogunate.

His epithet 'Sword-Master Shogun' gives him a unique presence in the Sengoku era. The image of his last stand—switching famous swords one after another—has been retold for centuries, and his determination to uphold shogunal dignity inspires fiction to this day.