Isshi incident

The Isshi incident (乙巳の変, Isshi no Hen) refers to the assassination of Soga no Iruka and the political upheaval that followed, named for the zodiacal designation of the year 645. The killing was orchestrated by Nakatomi no Kamatari (later Fujiwara no Kamatari) and Prince Naka no Ōe as part of a plot to eliminate the main branch of the powerful Soga clan.

The assassination took place on July 10, 645 (12th day of the 6th month by the traditional Japanese calendar), during a court ceremony at which memorials from the Three Kingdoms of Korea were being read to Empress Kōgyoku by Ishikawa no Maro. Prince Naka no Ōe had reportedly made detailed preparations: closing the palace gates, bribing palace guards, concealing a spear in the ceremonial hall, and arranging for four armed men to attack Iruka. When those men hesitated out of fear, Naka no Ōe himself rushed at Iruka and wounded his head and shoulder. Iruka survived the initial attack long enough to protest his innocence and request an investigation before Empress Kōgyoku. While she withdrew to consider the matter, the four guards returned and killed Iruka. Soon afterward, Iruka's father, Soga no Emishi, took his own life by setting fire to his residence, a blaze that destroyed the manuscript copy of the Tennōki and other imperial records, though Fune no Fubitoesaka is said to have rescued the burning Kokki from the flames before presenting it to Naka no Ōe; no surviving copies of that work are known.

The violence occurred in Empress Kōgyoku's presence, and in the context of Asuka-period sensitivities around ritual "pollution," the event prompted her decision to abdicate. Although she initially wished to pass the throne directly to Naka no Ōe, Nakatomi no Kamatari advised that succession instead go to her older brother, Furuhito no Ōe, or her maternal uncle, Prince Karu. Furuhito no Ōe resolved this by renouncing his claim and taking Buddhist tonsure at Hōkō-ji on the same day, traditionally dated July 12, 645. Kōgyoku then abdicated in favor of her brother, who became Emperor Kōtoku. Kōgyoku later returned to the throne as Empress Saimei, and Naka no Ōe eventually became Emperor Tenji.

A passage in the Nihon Shoki records Furuhito no Ōe exclaiming that Iruka was "killed by a Korean," a line whose meaning has prompted multiple competing scholarly interpretations, including theories about disguised conspirators or the ethnic identity of the plotters, none of which the source text resolves definitively.

This is a historical incident from 7th-century Japan; no individuals are named as criminally "convicted," "charged," "acquitted," or "exonerated" under the categories used for modern case documentation, and no living victims or law-enforcement figures are involved.