Born around 631 as younger brother of Emperor Tenji. After Tenji's death he retired to Yoshino, seemingly as a monk, but resolved to take up arms. In the Jinshin War of 672, he rallied provincial warriors and defeated the forces of his nephew Prince Otomo at multiple locations, seizing power within months. As Emperor Tenmu he worked to establish the absolute sacred authority of the emperor, cementing the use of the titles "Tenno" and "Nihon." He broke with the clan confederation model and championed direct imperial rule. He ordered the compilation of the Asuka Kiyomihara Code to consolidate the ritsuryō state. In 681, he commanded Hieda no Are to memorize imperial chronicles—the seed of both the Kojiki and Nihon Shoki. He also organized the Ise Shrine and its rebuilding cycle, and sponsored major Buddhist construction. He died in 686, having decisively shaped the form of the Japanese imperial state.

Initially showed caution by taking Buddhist vows and retreating to Yoshino after Tenji's death, but acted swiftly once he raised arms. A charismatic leader with combined military talent.

Established the emperor-centered ritsuryō state, shaping ancient Japan's final form. The Kojiki and Nihon Shoki compilations became the starting point of Japanese historical consciousness.