Choroku no Hen (長禄の変)
Choroku no hen was an incident that occurred on December 27, 1457 during the Muromachi period when former retainers of the Akamatsu family attacked angu (emperor's temporary palace) of Gonancho (Second Southern Court), made a surprise assault on the brothers of Sonshuo and Chugio who were descendants of the Southern Court emperor (the latter was a seii taishogun (literally, "great general who subdues the barbarians" of the Southern Court), and took away Shinji (the sacred jewel).
Summary
"Yasakani no magatama" (curved jewels), one of the sanshu no jingi (the three imperial regalia), had been carried away and kept by the Gonancho in the Kinketsu incident in 1443.
The former retainers of the shugo daimyo (military governor) Akamatsu clan which had been broken in the Kakitsu disturbance (Taro IWAMI, Tatewaki NYUNOYA, Mitsuyoshi KOZUKI, and so forth) who were determined to reestablish the clan noticed the fact. Together with Hiromitsu OGAWA, gozoku (powerful kin group) in Yamato Province, the retainers attacked the angu of the Gonancho, based in Kitayama and Kawakami deep in Yoshino, on December 27, 1457, they defeated the brothers of Jitenno and Chugio who were descendants of the Southern Court emperor (the latter was a seii taishogun of the Gonancho), and took away the Shinji. But the Shinji was later recaptured by the people of Yoshino who supported the Gonancho.
The retainers attacked the residence of Jinenno's mother the following year 1458, and took away the Shinji again. Thereafter, the Muromachi bakufu (Japanese feudal government headed by a shogun) admired their success in taking back the Shinji, which had been carried away from Kyoto for 15 years prior, and permitted them to reestablish the Akamatsu clan.