Daiei was an era from 8/23 of 1521 to 8/20 of 1528 (based on the Japanese lunisolar calendar) in the Sengoku period.
The change from the prior era known as Eishō was related to circumstances of war and natural disasters.
During this era, Gokashiwabara, followed by Gonara, served as the emperors; Ashikaga Yoshitane (1490-1495 and 1508-1522), followed by Ashikaga Yoshiharu (1522-1546), served respectively as the tenth and twelfth shōguns of the Muromachi bakufu.
- Ashikaga Kameōmaru was appointed Chief of the Right Division of Horses, an event presided over by Hosokawa Takakuni as the deputy shōgun. This represented a formal acknowledgement of a plan for Kameōmaru to serve as the next shōgun, which occurred in fact early in 1522.
- The Ningbo Incident (Ninpo no ran), witnessed a clash between the Hosokawa and Ōuchi clans in the harbor of Ningbo, China in a dispute over exclusive trading rights with the Ming dynasty.
- Ashikaga Yoshitane, the tenth shōgun, died.
- The Daiei Discord (Daiei no naikō) was an internal disturbance within the Shimotsuke-Utsunomiya clan in which Utsunomiya Tadatsuna, the eighteenth head of the clan, was challenged by retainers of the Haga clan, led by Haga Takatsune.
- Amago Tsunehisa, a daimyō and deputy military governor of Izumo Province, led an incursion into Hōki Province known as the Collapse in the Fifth Month of Daiei (Daiei-no-satsuki kuzure). Beginning in the Eishō era, Tsunehisa intervened in an internal disputes in the Yamana clan of Hōki regarding the role of military governor. During the Daiei era, Tsunehisa enabled Yamana Sumiyuki to become the military governor and sent Amago Haruhisa to serve as the deputy military governor, imposing control over governance of the province.
- Imagawa Ujichika, the military governor of Suruga Province, promulgated a set of thirty-three covenants governing clan affairs, known as the Imagawa kana mokuroku.
- Hosokawa Takakuni, the deputy shōgun, executed one of his capable retainers, Kōzai Motomori, based on slander by allies. This led to internal discord within Hosokawa Takakuni’s family in which Kōzai’s older brothers, Hatano Tanemichi and Yanagimoto Kataharu, separated from the clan.
- Hosokawa Rokurō, the orphan of Hosokawa Sumimoto who died in 1520, raised arms from Awa Province in Shikoku in a bid to overthrow Hosokawa Takakuni, a former rival of Sumimoto.
- Gokashiwabara, the 104th emperor to the throne, died.
- The succession struggle for control of the Hosokawa clan reignited, with the faction led by Rokurō entering the Kinai Region by the end of the year, converging with the Hatano forces that had separated from Takakuni.
- In the Battle of Katsurakawara, Hosokawa Takakuni, the deputy shōgun, lost overwhelmingly to allied forces under Hosokawa Rokurō, whereupon Takakuni paid tribute to Ashikaga Yoshiharu, the shōgun, and fled Kyōto for safety. In addition to Takakuni, the hyōjōshū and bugyōnin, officials and advisors who served in the bakufu administration, also departed, paralyzing the ability of the bakufu to govern.