On the twelfth day of the first month of the fourth year of the Shōtoku era (February 26, 1714, by the Western calendar), Ejima, a high-ranking lady in the Ōoku, visited the grave of the late shōgun Tokugawa Ienobu as a proxy for her superior, Gekkō-in, who had been a lady-in-waiting to the late shōgun and was the mother of the ruling shōgun Tokugawa Ietsugu. Ejima then accepted an invitation to attend a kabuki performance by the popular actor Ikushima Shingorō at the Yamamura-za. After the performance, she invited the actor and others to a party at a tea house.
The party ran late and Ejima missed the closing of the gates to the Ōoku. As she went from one gate to the next trying to gain entry, word of her situation reached the officials within, and Ejima became the focus of a power struggle between her superior Gekkō-in, and Gekkō-in's rival Ten'ei-in, the wife of the late Ienobu. They in turn were part of a larger power struggle between two factions. One faction was led by Arai Hakuseki and Manabe Akifusa, the two closest advisors to both Ienobu and Ietsugu. The other was headed by fudai daimyōs and the rōjū who had been in office since the time of the fifth shōgun Tokugawa Tsunayoshi.
Ten'ei-in seized the opportunity to launch an investigation of the Ōoku. Numerous infractions were discovered, and ultimately 1,300 people were punished. Ejima was sentenced to death, but she received a pardon, and was placed in custody of the Takatō Domain. Her brother was sentenced to die by seppuku. Ikushima was banished to the island of Miyake-jima and the Yamamura-za was disbanded. Over a century later the kabuki theatres were relocated to Asakusa, farther from Edo Castle.
Within the Ōoku, Ten'ei-in emerged victorious. The following year, when Ietsugu died, she supported Tokugawa Yoshimune, the successful contender for the shogunate.
The Ejima-Ikushima affair has been dramatized in kabuki, and has been the subject of nagauta chants. Numerous films and television dramas have portrayed the event. The 2006 film Oh! Oku stars Yukie Nakama as Ejima and Hidetoshi Nishijima as Ikushima Shingorō. A 1971 television series featured Ineko Arima as Ejima, and kabuki actor Takao Kataoka (now Kataoka Nizaemon XV) as Ikushima.
- 新井政義（編集者）『日本史事典』。東京：旺文社１９８７(p. 50)
- 竹内理三（編）『日本史小辞典』。東京：角川書店１９８５(p. 314)